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Liu J, Li Y, Zhang A, Zhong H, Jiang H, Tsui MTK, Li M, Pan K. Impact of geochemistry and microbes on the methylmercury production in mangrove sediments. JOURNAL OF HAZARDOUS MATERIALS 2024; 479:135627. [PMID: 39217948 DOI: 10.1016/j.jhazmat.2024.135627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Revised: 08/05/2024] [Accepted: 08/21/2024] [Indexed: 09/04/2024]
Abstract
Unraveling the geochemical and microbial controls on methylmercury (MeHg) dynamics in mangrove sediments is important, as MeHg can potentially pose risks to marine biota and people that rely on these ecosystems. While the important role of sulfate-reducing bacteria in MeHg formation has been examined in this ecologically important habitat, the contribution of non-Hg methylating communities on MeHg production remains particularly unclear. Here, we collected sediment samples from 13 mangrove forests in south China and examined the geochemical parameters and microbial communities related to the Hg methylation. MeHg concentrations were significantly correlated to the OM-related parameters such as organic carbon content, total nitrogen, and dissolved organic carbon concentrations, suggesting the importance of OM in the MeHg production. Sulfate-reducing bacteria were the major Hg-methylators in mangrove sediments. Desulfobacteraceae and Desulfobulbaceae dominated the Hg-methylating microbes. Classification random forest analysis detected strong co-occurrence between Hg methylators and putative non-Hg methylators, thus suggesting that both types of microorganisms contribute to the MeHg dynamics in the sediments. Our study provides an overview of MeHg contamination in south China and advances our understanding of Hg methylation in mangrove ecosystems.
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Affiliation(s)
- Jingli Liu
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Yanping Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Aijia Zhang
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu Province 210046, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Martin Tsz-Ki Tsui
- School of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin 999077, Hong Kong, China
| | - Meng Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Ke Pan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China.
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2
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Fang K, He Y, Xu J, Shi J. Synchronous influence of soil amendments on alkylmercury and methane emissions in mercury-contaminated paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 946:174415. [PMID: 38969116 DOI: 10.1016/j.scitotenv.2024.174415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/25/2024] [Accepted: 06/29/2024] [Indexed: 07/07/2024]
Abstract
Mercury (Hg) alkylation and methane (CH4) emissions pose significant global concerns. Paddy soil, due to its long-term anaerobic conditions and abundant organic matter, is hotspots for soil Hg alkylation and CH4 emissions. However, the relevance between Hg alkylation and CH4 emissions, especially their simultaneous reduction strategies, remains poorly understood. Here, we investigated the effects of biochar (BC), selenium (Se) and rice straw (RS) amendments on Hg alkylation and CH4 emissions in paddy soil, and the accumulation of Hg speciation. Results found that both BC and RS amendments significantly increased the levels of soil organic carbon (SOC) and humification index (HIX). Furthermore, BC decreased the concentrations of Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) by 63.1%, 53.6% and 100% in rice grains. However, RS increased Hg(II) concentration but decreased the total Hg (THg), MeHg and EtHg concentrations in rice grains. Compared to the CK, RS significantly increased CH4 emissions, while BC decreased CH4 emissions, and Se showed no significant difference. Se amendment increased the Hg(II) and EtHg concentrations by 20.3% and 17.0% respectively, and decreased the MeHg concentration in grains by 58.3%. Both BC and RS impacted the abundance of methanogens by enhancing SOC and HIX, subsequently modulating the relevance between Hg alkylation and CH4 emissions. These findings provide insights into the relevance between Hg alkylation and CH4 emissions and propose potential mitigation mechanisms in Hg-contaminated paddy soil.
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Affiliation(s)
- Kaikai Fang
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yan He
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, Hangzhou 310058, China
| | - Jianming Xu
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jiachun Shi
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
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3
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Liang H, Wang S, Xu P, Wang M, Liang P, Wu S, Zhang J, Wong MH. Converting flooded rice to dry farming can alleviate MeHg accumulation in grains. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 283:116817. [PMID: 39083863 DOI: 10.1016/j.ecoenv.2024.116817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 07/22/2024] [Accepted: 07/27/2024] [Indexed: 08/02/2024]
Abstract
The study explored the impact of water management on rice cultivation in mercury-contaminated paddy soil. The objective was to analyze the characteristics of mercury translocation by converting flooded soils to dry farming (non-flooded) to alleviate mercury accumulation in rice grains. The experiment was conducted over three consecutive rice-growing seasons, employing two distinct water management models: a continuously flooded rice cultivation mode and a flooded rice planting mode in the first season, followed by a non-flooded rice farming mode in the second and third seasons. The results showed that the change from flooded to non-flooded rice cultivation patterns presented extremely excellent environmental potential for inhibiting the uptake of both methylmercury and total mercury in rice. When transitioning from flooded cultivation to dry farming, the concentration of methylmercury and total mercury in the grains of non-flooded rice decreased by 87.15 % and 9.57 %, respectively, compared to that in the grains of flooded rice. In the third season, the methylmercury and total mercury in the grains of non-flooded rice decreased further by 95.03 % and 69.45 %, respectively. This study verified that the conversion of rice cultivation from flooded to non-flooded is an efficient strategy for suppressing the accumulation of methylmercury in rice grains, and it might offer a promising solution for managing soil mercury risks and ensuring the safety of rice for human consumption.
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Affiliation(s)
- Huang Liang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China
| | - Shan Wang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China; School of Geography and Resource Science, Neijiang Normal University, Neijiang 641100, China
| | - Ping Xu
- China National Rice Research Institute, Hangzhou 311401, China
| | - Minyan Wang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China.
| | - Peng Liang
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China; Zhejiang Province Key Laboratory of Soil Contamination and Bioremediation, Hangzhou 311300, China
| | - Shengchun Wu
- School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China; Zhejiang Province Key Laboratory of Soil Contamination and Bioremediation, Hangzhou 311300, China
| | - Jin Zhang
- School of Environment and Natural Resources, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Ming Hung Wong
- Consortium on Health, Environment, Education, and Research (CHEER), Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong Special Administrative Region of China
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Li Y, Zhang H, Guan Y, Cheng G, Li Z, Li Z, Cao M, Yin Y, Hu L, Shi J, Chen B. Functional genes and microorganisms controlling in situ methylmercury production and degradation in marine sediments: A case study in the Eastern China Coastal Seas. JOURNAL OF HAZARDOUS MATERIALS 2024; 476:134965. [PMID: 38905972 DOI: 10.1016/j.jhazmat.2024.134965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 06/17/2024] [Accepted: 06/17/2024] [Indexed: 06/23/2024]
Abstract
Dominant microorganisms and functional genes, including hgcA, hgcB, merA, and merB, have been identified to be responsible for mercury (Hg) methylation or methylmercury (MeHg) demethylation. However, their in situ correlation with MeHg levels and the processes of Hg methylation and MeHg demethylation in coastal areas remains poorly understood. In this study, four functional genes related to Hg methylation and MeHg demethylation (hgcA, hgcB, merA, and merB) were all detected in the sediments of the Eastern China Coastal Seas (ECCSs) (representative coastal seas highly affected by human activities) using metagenomic approaches. HgcA was identified to be the key gene controlling the in situ net production of MeHg in the ECCSs. Based on metagenomic analysis and incubation experiments, sulfate-reducing bacteria were identified as the dominant microorganisms controlling Hg methylation in the ECCSs. In addition, hgcA gene was positively correlated with the MeHg content and Hg methylation rates, highlighting the potential roles of Hg methylation genes and microorganisms influenced by sediment physicochemical properties in MeHg cycling in the ECCSs. These findings highlighted the necessity of conducting similar studies in other natural systems for elucidating the molecular mechanisms underlying MeHg production in aquatic environments.
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Affiliation(s)
- Yanbin Li
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Huimin Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Yingjun Guan
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Guoyi Cheng
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Zhaohong Li
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-sen University, Zhuhai 519082, China
| | - Zhuang Li
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-sen University, Zhuhai 519082, China
| | - Mengxi Cao
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yongguang Yin
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Ligang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Jianbo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Baowei Chen
- Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-sen University, Zhuhai 519082, China.
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Boie F, Ducey TF, Xing Y, Wang J, Rinklebe J. Field-aged rice hull biochar stimulated the methylation of mercury and altered the microbial community in a paddy soil under controlled redox condition changes. JOURNAL OF HAZARDOUS MATERIALS 2024; 472:134446. [PMID: 38696958 DOI: 10.1016/j.jhazmat.2024.134446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/25/2024] [Accepted: 04/25/2024] [Indexed: 05/04/2024]
Abstract
Mercury (Hg) contaminated paddy soils are hot spots for methylmercury (MeHg) which can enter the food chain via rice plants causing high risks for human health. Biochar can immobilize Hg and reduce plant uptake of MeHg. However, the effects of biochar on the microbial community and Hg (de)methylation under dynamic redox conditions in paddy soils are unclear. Therefore, we determined the microbial community in an Hg contaminated paddy soil non-treated and treated with rice hull biochar under controlled redox conditions (< 0 mV to 600 mV) using a biogeochemical microcosm system. Hg methylation exceeded demethylation in the biochar-treated soil. The aromatic hydrocarbon degraders Phenylobacterium and Novosphingobium provided electron donors stimulating Hg methylation. MeHg demethylation exceeded methylation in the non-treated soil and was associated with lower available organic matter. Actinobacteria were involved in MeHg demethylation and interlinked with nitrifying bacteria and nitrogen-fixing genus Hyphomicrobium. Microbial assemblages seem more important than single species in Hg transformation. For future directions, the demethylation potential of Hyphomicrobium assemblages and other nitrogen-fixing bacteria should be elucidated. Additionally, different organic matter inputs on paddy soils under constant and dynamic redox conditions could unravel the relationship between Hg (de)methylation, microbial carbon utilization and nitrogen cycling.
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Affiliation(s)
- Felizitas Boie
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany
| | - Thomas F Ducey
- US Department of Agriculture, Coastal Plains Soil, Water, Plant Research Center, 2611 West Lucas Street, Florence, SC, USA
| | - Ying Xing
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550002, PR China
| | - Jianxu Wang
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550082 Guiyang, P.R. China
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany.
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Zhang K, Pu Q, Liu J, Hao Z, Zhang L, Zhang L, Fu X, Meng B, Feng X. Using Mercury Stable Isotopes to Quantify Directional Soil-Atmosphere Hg(0) Exchanges in Rice Paddy Ecosystems: Implications for Hg(0) Emissions to the Atmosphere from Land Surfaces. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:11053-11062. [PMID: 38867369 DOI: 10.1021/acs.est.4c02143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Gaseous elemental mercury [Hg(0)] emissions from soils constitute a large fraction of global total Hg(0) emissions. Existing studies do not distinguish biotic- and abiotic-mediated emissions and focus only on photoreduction mediated emissions, resulting in an underestimation of soil Hg(0) emissions into the atmosphere. In this study, directional mercury (Hg) reduction pathways in paddy soils were identified using Hg isotopes. Results showed significantly different isotopic compositions of Hg(0) between those produced from photoreduction (δ202Hg = -0.80 ± 0.67‰, Δ199Hg = -0.38 ± 0.18‰), microbial reduction (δ202Hg = -2.18 ± 0.25‰, Δ199Hg = 0.29 ± 0.38‰), and abiotic dark reduction (δ202Hg = -2.31 ± 0.25‰, Δ199Hg = 0.50 ± 0.22‰). Hg(0) exchange fluxes between the atmosphere and the paddy soils were dominated by emissions, with the average flux ranging from 2.2 ± 5.7 to 16.8 ± 21.7 ng m-2 h-1 during different sampling periods. Using an isotopic signature-based ternary mixing model, we revealed that photoreduction is the most important contributor to Hg(0) emissions from paddy soils. Albeit lower, microbial and abiotic dark reduction contributed up to 36 ± 22 and 25 ± 15%, respectively, to Hg(0) emissions on the 110th day. These novel findings can help improve future estimation of soil Hg(0) emissions from rice paddy ecosystems, which involve complex biotic-, abiotic-, and photoreduction processes.
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Affiliation(s)
- Kun Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Zhengdong Hao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lijuan Zhang
- Key Laboratory for Heavy Metal Pollution Control and Reutilization, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Leiming Zhang
- Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto, Ontario M3H 5T4, Canada
| | - Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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7
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Zhang Q, Pu Q, Hao Z, Liu J, Zhang K, Meng B, Feng X. Warming inhibits Hg II methylation but stimulates methylmercury demethylation in paddy soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 930:172832. [PMID: 38688367 DOI: 10.1016/j.scitotenv.2024.172832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 04/25/2024] [Accepted: 04/26/2024] [Indexed: 05/02/2024]
Abstract
Inorganic mercury (HgII) can be transformed into neurotoxic methylmercury (MeHg) by microorganisms in paddy soils, and the subsequent accumulation in rice grains poses an exposure risk for human health. Warming as an important manifestation of climate change, changes the composition and structure of microbial communities, and regulates the biogeochemical cycles of Hg in natural environments. However, the response of specific HgII methylation/demethylation to the changes in microbial communities caused by warming remain unclear. Here, nationwide sampling of rice paddy soils and a temperature-adjusted incubation experiment coupled with isotope labeling technique (202HgII and Me198Hg) were conducted to investigate the effects of temperature on HgII methylation, MeHg demethylation, and microbial mechanisms in paddy soils along Hg gradients. We showed that increasing temperature significantly inhibited HgII methylation but promoted MeHg demethylation. The reduction in the relative abundance of Hg-methylating microorganisms and increase in the relative abundance of MeHg-demethylating microorganisms are the likely reasons. Consequently, the net Hg methylation production potential in rice paddy soils was largely inhibited under the increasing temperature. Collectively, our findings offer insights into the decrease in net MeHg production potential associated with increasing temperature and highlight the need for further evaluation of climate change for its potential effect on Hg transformation in Hg-sensitive ecosystems.
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Affiliation(s)
- Qianshuo Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Zhengdong Hao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; College of Resources, Sichuan Agricultural University, Chengdu 611130, China
| | - Kun Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
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8
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Zhong H, Su Y, Wu X, Nunes L, Li C, Hao Y, Liu YR, Tang W. Mercury supply limits methylmercury production in paddy soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 927:172335. [PMID: 38604369 DOI: 10.1016/j.scitotenv.2024.172335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/18/2024] [Accepted: 04/07/2024] [Indexed: 04/13/2024]
Abstract
The neurotoxic methylmercury (MeHg) is a product of inorganic mercury (IHg) after microbial transformation. Yet it remains unclear whether microbial activity or IHg supply dominates Hg methylation in paddies, hotspots of MeHg formation. Here, we quantified the response of MeHg production to changes in microbial activity and Hg supply using 63 paddy soils under the common scenario of straw amendment, a globally prevalent agricultural practice. We demonstrate that the IHg supply is the limiting factor for Hg methylation in paddies. This is because IHg supply is generally low in soils and can largely be facilitated (by 336-747 %) by straw amendment. The generally high activities of sulfate-reducing bacteria (SRB) do not limit Hg methylation, even though SRB have been validated as the predominant microbial Hg methylators in paddies in this study. These findings caution against the mobilization of legacy Hg triggered by human activities and climate change, resulting in increased MeHg production and the subsequent flux of this potent neurotoxin to our dining tables.
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Affiliation(s)
- Huan Zhong
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Yao Su
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Xinda Wu
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Luís Nunes
- Faculty of Sciences and Technology, Civil Engineering Research and Innovation for Sustainability Center, University of Algarve, Faro, Portugal
| | - Chengjun Li
- Institute of Environmental Research at Greater Bay Area, Guangzhou University, Guangzhou, Guangdong Province, China
| | - Yunyun Hao
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, Hubei Province, China
| | - Wenli Tang
- School of Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
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9
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Masuda Y, Mise K, Xu Z, Zhang Z, Shiratori Y, Senoo K, Itoh H. Global soil metagenomics reveals distribution and predominance of Deltaproteobacteria in nitrogen-fixing microbiome. MICROBIOME 2024; 12:95. [PMID: 38790049 PMCID: PMC11127431 DOI: 10.1186/s40168-024-01812-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 04/09/2024] [Indexed: 05/26/2024]
Abstract
BACKGROUND Biological nitrogen fixation is a fundamental process sustaining all life on earth. While distribution and diversity of N2-fixing soil microbes have been investigated by numerous PCR amplicon sequencing of nitrogenase genes, their comprehensive understanding has been hindered by lack of de facto standard protocols for amplicon surveys and possible PCR biases. Here, by fully leveraging the planetary collections of soil shotgun metagenomes along with recently expanded culture collections, we evaluated the global distribution and diversity of terrestrial diazotrophic microbiome. RESULTS After the extensive analysis of 1,451 soil metagenomic samples, we revealed that the Anaeromyxobacteraceae and Geobacteraceae within Deltaproteobacteria are ubiquitous groups of diazotrophic microbiome in the soils with different geographic origins and land usage types, with particular predominance in anaerobic soils (paddy soils and sediments). CONCLUSION Our results indicate that Deltaproteobacteria is a core bacterial taxon in the potential soil nitrogen fixation population, especially in anaerobic environments, which encourages a careful consideration on deltaproteobacterial diazotrophs in understanding terrestrial nitrogen cycling. Video Abstract.
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Affiliation(s)
- Yoko Masuda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Kazumori Mise
- National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, 2-17-2-1 Tsukisamu-higashi, Toyohira, Sapporo, Hokkaido, 062-8517, Japan.
| | - Zhenxing Xu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Zhengcheng Zhang
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Yutaka Shiratori
- Niigata Agricultural Research Institute, 857 Nagakura-machi, Nagaoka, Niigata, 940-0826, Japan
| | - Keishi Senoo
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Hideomi Itoh
- National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, 2-17-2-1 Tsukisamu-higashi, Toyohira, Sapporo, Hokkaido, 062-8517, Japan.
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10
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Chen KH, Feng J, Bodelier PLE, Yang Z, Huang Q, Delgado-Baquerizo M, Cai P, Tan W, Liu YR. Metabolic coupling between soil aerobic methanotrophs and denitrifiers in rice paddy fields. Nat Commun 2024; 15:3471. [PMID: 38658559 PMCID: PMC11043409 DOI: 10.1038/s41467-024-47827-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 04/15/2024] [Indexed: 04/26/2024] Open
Abstract
Paddy fields are hotspots of microbial denitrification, which is typically linked to the oxidation of electron donors such as methane (CH4) under anoxic and hypoxic conditions. While several anaerobic methanotrophs can facilitate denitrification intracellularly, whether and how aerobic CH4 oxidation couples with denitrification in hypoxic paddy fields remains virtually unknown. Here we combine a ~3300 km field study across main rice-producing areas of China and 13CH4-DNA-stable isotope probing (SIP) experiments to investigate the role of soil aerobic CH4 oxidation in supporting denitrification. Our results reveal positive relationships between CH4 oxidation and denitrification activities and genes across various climatic regions. Microcosm experiments confirm that CH4 and methanotroph addition promote gene expression involved in denitrification and increase nitrous oxide emissions. Moreover, 13CH4-DNA-SIP analyses identify over 70 phylotypes harboring genes associated with denitrification and assimilating 13C, which are mostly belonged to Rubrivivax, Magnetospirillum, and Bradyrhizobium. Combined analyses of 13C-metagenome-assembled genomes and 13C-metabolomics highlight the importance of intermediates such as acetate, propionate and lactate, released during aerobic CH4 oxidation, for the coupling of CH4 oxidation with denitrification. Our work identifies key microbial taxa and pathways driving coupled aerobic CH4 oxidation and denitrification, with important implications for nitrogen management and greenhouse gas regulation in agroecosystems.
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Affiliation(s)
- Kang-Hua Chen
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation and Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jiao Feng
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation and Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Paul L E Bodelier
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), PO Box 50, 6700 AB, Wageningen, The Netherlands
| | - Ziming Yang
- Department of Chemistry, Oakland University, Rochester, MI, 48309, USA
| | - Qiaoyun Huang
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation and Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China
| | - Manuel Delgado-Baquerizo
- Laboratorio de Biodiversidad y Funcionamiento Ecosistémico, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Sevilla, 41012, Spain
| | - Peng Cai
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation and Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wenfeng Tan
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation and Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yu-Rong Liu
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation and Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China.
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11
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Wang YL, Ikuma K, Brooks SC, Varonka MS, Deonarine A. Non-mercury methylating microbial taxa are integral to understanding links between mercury methylation and elemental cycles in marine and freshwater sediments. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123573. [PMID: 38365074 DOI: 10.1016/j.envpol.2024.123573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 01/09/2024] [Accepted: 02/13/2024] [Indexed: 02/18/2024]
Abstract
The goal of this study was to explore the role of non-mercury (Hg) methylating taxa in mercury methylation and to identify potential links between elemental cycles and Hg methylation. Statistical approaches were utilized to investigate the microbial community and biochemical functions in relation to methylmercury (MeHg) concentrations in marine and freshwater sediments. Sediments were collected from the methylation zone (top 15 cm) in four Hg-contaminated sites. Both abiotic (e.g., sulfate, sulfide, iron, salinity, total organic matter, etc.) and biotic factors (e.g., hgcA, abundances of methylating and non-methylating taxa) were quantified. Random forest and stepwise regression were performed to assess whether non-methylating taxa were significantly associated with MeHg concentration. Co-occurrence and functional network analyses were constructed to explore associations between taxa by examining microbial community structure, composition, and biochemical functions across sites. Regression analysis showed that approximately 80% of the variability in sediment MeHg concentration was predicted by total mercury concentration, the abundances of Hg methylating taxa, and the abundances of the non-Hg methylating taxa. The co-occurrence networks identified Paludibacteraceae and Syntrophorhabdaceae as keystone non Hg methylating taxa in multiple sites, indicating the potential for syntrophic interactions with Hg methylators. Strong associations were also observed between methanogens and sulfate-reducing bacteria, which were likely symbiotic associations. The functional network results suggested that non-Hg methylating taxa play important roles in sulfur respiration, nitrogen respiration, and the carbon metabolism-related functions methylotrophy, methanotrophy, and chemoheterotrophy. Interestingly, keystone functions varied by site and did not involve carbon- and sulfur-related functions only. Our findings highlight associations between methylating and non-methylating taxa and sulfur, carbon, and nitrogen cycles in sediment methylation zones, with implications for predicting and understanding the impact of climate and land/sea use changes on Hg methylation.
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Affiliation(s)
- Yong-Li Wang
- Department of Civil, Environmental & Construction Engineering, Texas Tech University, Lubbock, TX, United States
| | - Kaoru Ikuma
- Department of Civil, Construction & Environmental Engineering, Iowa State University, Ames, IA, United States
| | - Scott C Brooks
- Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States
| | - Matthew S Varonka
- U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA, United States
| | - Amrika Deonarine
- Department of Civil, Environmental & Construction Engineering, Texas Tech University, Lubbock, TX, United States.
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12
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Zhong H, Tang W, Li Z, Sonne C, Lam SS, Zhang X, Kwon SY, Rinklebe J, Nunes LM, Yu RQ, Gu B, Hintelmann H, Tsui MTK, Zhao J, Zhou XQ, Wu M, Liu B, Hao Y, Chen L, Zhang B, Tan W, Zhang XX, Ren H, Liu YR. Soil Geobacteraceae are the key predictors of neurotoxic methylmercury bioaccumulation in rice. NATURE FOOD 2024; 5:301-311. [PMID: 38605129 DOI: 10.1038/s43016-024-00954-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 03/05/2024] [Indexed: 04/13/2024]
Abstract
Contamination of rice by the potent neurotoxin methylmercury (MeHg) originates from microbe-mediated Hg methylation in soils. However, the high diversity of Hg methylating microorganisms in soils hinders the prediction of MeHg formation and challenges the mitigation of MeHg bioaccumulation via regulating soil microbiomes. Here we explored the roles of various cropland microbial communities in MeHg formation in the potentials leading to MeHg accumulation in rice and reveal that Geobacteraceae are the key predictors of MeHg bioaccumulation in paddy soil systems. We characterized Hg methylating microorganisms from 67 cropland ecosystems across 3,600 latitudinal kilometres. The simulations of a rice-paddy biogeochemical model show that MeHg accumulation in rice is 1.3-1.7-fold more sensitive to changes in the relative abundance of Geobacteraceae compared to Hg input, which is recognized as the primary parameter in controlling MeHg exposure. These findings open up a window to predict MeHg formation and accumulation in human food webs, enabling more efficient mitigation of risks to human health through regulations of key soil microbiomes.
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Affiliation(s)
- Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China.
- Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario, Canada.
| | - Wenli Tang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China
| | - Zizhu Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China
| | - Christian Sonne
- Department of Ecoscience, Aarhus University, Roskilde, Denmark.
- Sustainability Cluster, School of Engineering, University of Petroleum and Energy Studies, Dehradun, India.
| | - Su Shiung Lam
- Higher Institution Centre of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries (AKUATROP), Universiti Malaysia Terengganu, Kuala Nerus, Malaysia
- Center for Global Health Research (CGHR), Saveetha Medical College, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha University, Chennai, India
| | - Xiao Zhang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China
| | - Sae Yun Kwon
- Division of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang, South Korea
| | - Jörg Rinklebe
- School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, University of Wuppertal, Wuppertal, Germany
| | - Luís M Nunes
- Faculty of Sciences and Technology, Civil Engineering Research and Innovation for Sustainability Center, University of Algarve, Faro, Portugal
| | - Ri-Qing Yu
- Department of Biology, Center for Environment, Biodiversity and Conservation, The University of Texas at Tyler, Tyler, TX, USA
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Holger Hintelmann
- Department of Chemistry, Trent University, Peterborough, Ontario, Canada
| | - Martin Tsz-Ki Tsui
- School of Life Sciences, Earth and Environmental Sciences Programme, Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong SAR, China
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong SAR, China
| | - Jiating Zhao
- Department of Environmental Science, Zhejiang University, Hangzhou, China
| | - Xin-Quan Zhou
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, China
| | - Mengjie Wu
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China
| | - Beibei Liu
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China
| | - Yunyun Hao
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, China
| | - Long Chen
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai, China.
| | - Baogang Zhang
- School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, China
| | - Wenfeng Tan
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, China
| | - Xu-Xiang Zhang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China
| | - Hongqiang Ren
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, China
| | - Yu-Rong Liu
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan, China.
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13
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Zheng Z, Hu J, He T, Liu C, Zhou X, Yin D. Suppression of mercury methylation in soil and methylmercury accumulation in rice by dissolved organic matter derived from sulfur-rich rape straw. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123657. [PMID: 38428787 DOI: 10.1016/j.envpol.2024.123657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/09/2024] [Accepted: 02/24/2024] [Indexed: 03/03/2024]
Abstract
Straw amendment significantly enhances mercury (Hg) methylation and subsequent methylmercury (MeHg) bioaccumulation in Hg-contaminated paddy fields by releasing dissolved organic matter (DOM). This study comprehensively investigates the regulatory mechanisms of DOM and its different molecular weights derived from sulfur-rich rape straw (RaDOM) and composted rape straw (CRaDOM) applied in the rice-filling stage on soil MeHg production and subsequent bioaccumulation in rice grains. The results indicated that the amendment of RaDOM and CRaDOM significantly reduced soil MeHg content by 42.40-62.42%. This reduction can be attributed to several factors, including the suppression of Hg-methylating bacteria in soil, the supply of sulfate from RaDOM and CRaDOM, and the increase in the humification, molecular weight, and humic-like fractions of soil DOM. Additionally, adding RaDOM increased the MeHg bioaccumulation factor in roots by 27.55% while inhibiting MeHg transportation by 12.24% and ultimately reducing MeHg content in grains by 21.24% compared to the control group. Similarly, CRaDOM enhanced MeHg accumulation by 25.19%, suppressed MeHg transportation by 39.65%, and reduced MeHg levels in the grains by 27.94%. The assimilation of sulfate derived from RaDOM and CRaDOM into glutathione may be responsible for the increased retention of MeHg in the roots. Over the three days, there was a significant decrease in soil MeHg content as the molecular weight of RaDOM increased; conversely, altering the molecular weight of CRaDOM demonstrated an inverse trend. However, this pattern was not observed after 12 days. Applying sulfur-rich rape DOM can help mitigate MeHg accumulation in paddy fields by regulating the quality of soil DOM, sulfur cycling, and Hg-methylating bacteria.
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Affiliation(s)
- Zhoujuan Zheng
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Jie Hu
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Chengbin Liu
- Institute for Agri-food Standards and Testing Technology, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, China
| | - Xian Zhou
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang, 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China.
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14
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Zhang S, Xia M, Pan Z, Wang J, Yin Y, Lv J, Hu L, Shi J, Jiang T, Wang D. Soil organic matter degradation and methylmercury dynamics in Hg-contaminated soils: Relationships and driving factors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 356:120432. [PMID: 38479282 DOI: 10.1016/j.jenvman.2024.120432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 02/01/2024] [Accepted: 02/17/2024] [Indexed: 04/07/2024]
Abstract
Biodegradation of soil organic matter (SOM), which involves greenhouse gas (GHG) emissions, plays an essential role in the global carbon cycle. Over the past few decades, this has become an important research focus, particularly in natural ecosystems. SOM biodegradation significantly affects contaminants in the environment, such as mercury (Hg) methylation, producing highly toxic methylmercury (MeHg). However, the potential link between GHG production from SOM turnover in contaminated soils and biogeochemical processes involving contaminants remains unclear. In this study, we investigated the dynamics of GHG, MeHg production, and the relationship between biogeochemical processes in soils from two typical Hg mining sites. The two contaminated soils have different pathways, explaining the significant variations in GHG and MeHg production. The divergence of the microbial communities in these two biogeochemical processes is essential. In addition to the microbial role, abiotic factors such as Hg species can significantly affect MeHg production. On the other hand, we found an inverse relationship between CH4 and MeHg, suggesting that carbon emission reduction policies and management could inadvertently increase the MeHg levels. This highlights the need for an eclectic approach to organic carbon sequestration and contaminant containment. These findings suggest that it is difficult to establish a general pattern to describe and explain the SOM degradation and MeHg production in contaminated soils within the specific scenarios. However, this study provides a case study and helpful insights for further understanding the links between environmental risks and carbon turnover in Hg mining areas.
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Affiliation(s)
- Siqi Zhang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
| | - Meng Xia
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
| | - Zhaoyang Pan
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianxu Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Yongguang Yin
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Jitao Lv
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Ligang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Jianbo Shi
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China
| | - Tao Jiang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, 430056, China.
| | - Dingyong Wang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, Department of Environmental Sciences and Engineering, College of Resources and Environment, Southwest University, Chongqing, 400716, China
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15
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Guo P, Du H, Zhao W, Xiong B, Wang M, He M, Flemetakis E, Hänsch R, Ma M, Rennenberg H, Wang D. Selenium- and chitosan-modified biochars reduce methylmercury contents in rice seeds with recruiting Bacillus to inhibit methylmercury production. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133236. [PMID: 38141298 DOI: 10.1016/j.jhazmat.2023.133236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/13/2023] [Accepted: 12/10/2023] [Indexed: 12/25/2023]
Abstract
Biochar could reshape microbial communities, thereby altering methylmercury (MeHg) concentrations in rice rhizosphere and seeds. However, it remains unclear whether and how biochar amendment perturbs microbe-mediated MeHg production in mercury (Hg) contaminated paddy soil. Here, we used pinecone-derived biochar and its six modified biochars to reveal the disturbance. Results showed that selenium- and chitosan-modified biochar significantly reduced MeHg concentrations in the rhizosphere by 85.83% and 63.90%, thereby decreasing MeHg contents in seeds by 86.37% and 75.50%. The two modified bicohars increased the abundance of putative Hg-resistant microorganisms Bacillus, the dominant microbe in rhizosphere. These reductions about MeHg could be facilitated by biochar sensitive microbes such as Oxalobacteraceae and Subgroup_7. Pinecone-derived biochar increased MeHg concentration in rhizosphere but unimpacted MeHg content in seeds was observed. This biochar decreased the abundance in Bacillus but enhanced in putative Hg methylator Desulfovibrio. The increasing MeHg concentration in rhizosphere could be improved by biochar sensitive microbes such as Saccharimonadales and Clostridia. Network analysis showed that Saccharimonadales and Clostridia were the most prominent keystone taxa in rhizosphere, and the three biochars manipulated abundances of the microbes related to MeHg production in rhizosphere by those biochar sensitive microbes. Therefore, selenium- and chitosan-modified biochar could reduce soil MeHg production by these microorganisms, and is helpful in controlling MeHg contamination in rice.
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Affiliation(s)
- Pan Guo
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Hongxia Du
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Wancang Zhao
- Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, PR China
| | - Bingcai Xiong
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Mingxing Wang
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Chongqing 400715, PR China
| | - Mingyan He
- Chongqing Ecological Environment Monitoring Center, Chongqing 401147, PR China
| | - Emmanouil Flemetakis
- Laboratory of Molecular Biology, Department of Biotechnology, Agricultural University of Athens, 11855 Athens, Greece
| | - Robert Hänsch
- Institute for Plant Biology, Technische Universität Braunschweig, Humboldtstraße 1, D-38106, Braunschweig, Germany
| | - Ming Ma
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, PR China; Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, PR China.
| | - Heinz Rennenberg
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, PR China
| | - Dingyong Wang
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Chongqing 400715, PR China
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16
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Wu Z, Li Z, Shao B, Chen J, Cui X, Cui X, Liu X, Zhao YX, Pu Q, Liu J, He W, Liu Y, Liu Y, Wang X, Meng B, Tong Y. Differential response of Hg-methylating and MeHg-demethylating microbiomes to dissolved organic matter components in eutrophic lake water. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133298. [PMID: 38141310 DOI: 10.1016/j.jhazmat.2023.133298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/01/2023] [Accepted: 12/15/2023] [Indexed: 12/25/2023]
Abstract
Methylmercury (MeHg) production in aquatic ecosystems is a global concern because of its neurotoxic effect. Dissolved organic matter (DOM) plays a crucial role in biogeochemical cycling of Hg. However, owing to its complex composition, the effects of DOM on net MeHg production have not been fully understood. Here, the Hg isotope tracer technique combined with different DOM treatments was employed to explore the influences of DOM with divergent compositions on Hg methylation/demethylation and its microbial mechanisms in eutrophic lake waters. Our results showed that algae-derived DOM treatments enhanced MeHg concentrations by 1.42-1.53 times compared with terrestrial-derived DOM. Algae-derived DOM had largely increased the methylation rate constants by approximately 1-2 orders of magnitude compared to terrestrial-derived DOM, but its effects on demethylation rate constants were less pronounced, resulting in the enhancement of net MeHg formation. The abundance of hgcA and merB genes suggested that Hg-methylating and MeHg-demethylating microbiomes responded differently to DOM treatments. Specific DOM components (e.g., aromatic proteins and soluble microbial byproducts) were positively correlated with both methylation rate constants and the abundance of Hg-methylating microbiomes. Our results highlight that the DOM composition influences the Hg methylation and MeHg demethylation differently and should be incorporated into future Hg risk assessments in aquatic ecosystems.
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Affiliation(s)
- Zhengyu Wu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Zhike Li
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Bo Shao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Ji Chen
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xiaomei Cui
- School of Ecology and Environment, Tibet University, Lhasa 850000, China
| | - Xiaoyu Cui
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Xianhua Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Ying Xin Zhao
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Qiang Pu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Wei He
- School of Water Resource and Environment, China University of Geoscience (Beijing), Beijing 100083, China
| | - Yiwen Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Yurong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xuejun Wang
- College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Yindong Tong
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China; School of Ecology and Environment, Tibet University, Lhasa 850000, China.
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17
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Cardona GI, Escobar MC, Acosta-González A, Díaz-Ruíz N, Niño-García JP, Vasquez Y, Marrugo-Negrete J, Marqués S. Microbial diversity and abundance of Hg related genes from water, sediment and soil the Colombian amazon ecosystems impacted by artisanal and small-scale gold mining. CHEMOSPHERE 2024; 352:141348. [PMID: 38340998 DOI: 10.1016/j.chemosphere.2024.141348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/12/2024]
Abstract
The Amazon region abounds in precious mineral resources including gold, copper, iron, and coltan. Artisanal and small-scale gold mining (ASGM) poses a severe risk in this area due to considerable mercury release into the surrounding ecosystems. Nonetheless, the impact of mercury on both the overall microbiota and the microbial populations involved in mercury transformation is not well understood. In this study we evaluated microbial diversity in samples of soil, sediment and water potentially associated with mercury contamination in two localities (Taraira and Tarapacá) in the Colombian Amazon Forest. To this end, we characterized the bacterial community structure and mercury-related functions in samples from sites with a chronic history of mercury contamination which today have different levels of total mercury content. We also determined mercury bioavailability and mobility in the samples with the highest THg and MeHg levels (up to 43.34 and 0.049 mg kg-1, respectively, in Taraira). Our analysis of mercury speciation showed that the immobile form of mercury predominated in soils and sediments, probably rendering it unavailable to microorganisms. Despite its long-term presence, mercury did not appear to alter the microbial community structure or composition, which was primarily shaped by environmental and physicochemical factors. However, an increase in the relative abundance of merA genes was detected in polluted sediments from Taraira. Several Hg-responsive taxa in soil and sediments were detected in sites with high levels of THg, including members of the Proteobacteria, Acidobacteria, Actinobacteria, Firmicutes and Chloroflexi phyla. The results suggest that mercury contamination at the two locations sampled may select mercury-adapted bacteria carrying the merA gene that could be used in bioremediation processes for the region.
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Affiliation(s)
- Gladys Inés Cardona
- Instituto Amazónico de Investigaciones Científicas SINCHI. Laboratorio de Biotecnología y Recursos Genéticos, Bogotá, Colombia.
| | - Maria Camila Escobar
- Instituto Amazónico de Investigaciones Científicas SINCHI. Laboratorio de Biotecnología y Recursos Genéticos, Bogotá, Colombia; Escuela de Microbiología. Universidad de Antioquia, Medellín, Colombia
| | | | - Natalie Díaz-Ruíz
- Escuela de Microbiología. Universidad de Antioquia, Medellín, Colombia
| | | | - Yaneth Vasquez
- Chemistry Department, Universidad de Córdoba, Montería, Colombia
| | - José Marrugo-Negrete
- Convergence Science and Technology Cluster, Universidad Central, Bogotá, Colombia
| | - Silvia Marqués
- Department of Biotechnology and Environmental Protection. Estación Experimental Del Zaidín. Consejo Superior de Investigaciones Científicas, Granada, Spain
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18
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Peng X, Yang Y, Yang S, Li L, Song L. Recent advance of microbial mercury methylation in the environment. Appl Microbiol Biotechnol 2024; 108:235. [PMID: 38407657 PMCID: PMC10896945 DOI: 10.1007/s00253-023-12967-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/02/2023] [Accepted: 12/13/2023] [Indexed: 02/27/2024]
Abstract
Methylmercury formation is mainly driven by microbial-mediated process. The mechanism of microbial mercury methylation has become a crucial research topic for understanding methylation in the environment. Pioneering studies of microbial mercury methylation are focusing on functional strain isolation, microbial community composition characterization, and mechanism elucidation in various environments. Therefore, the functional genes of microbial mercury methylation, global isolations of Hg methylation strains, and their methylation potential were systematically analyzed, and methylators in typical environments were extensively reviewed. The main drivers (key physicochemical factors and microbiota) of microbial mercury methylation were summarized and discussed. Though significant progress on the mechanism of the Hg microbial methylation has been explored in recent decade, it is still limited in several aspects, including (1) molecular biology techniques for identifying methylators; (2) characterization methods for mercury methylation potential; and (3) complex environmental properties (environmental factors, complex communities, etc.). Accordingly, strategies for studying the Hg microbial methylation mechanism were proposed. These strategies include the following: (1) the development of new molecular biology methods to characterize methylation potential; (2) treating the environment as a micro-ecosystem and studying them from a holistic perspective to clearly understand mercury methylation; (3) a more reasonable and sensitive inhibition test needs to be considered. KEY POINTS: • Global Hg microbial methylation is phylogenetically and functionally discussed. • The main drivers of microbial methylation are compared in various condition. • Future study of Hg microbial methylation is proposed.
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Affiliation(s)
- Xuya Peng
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China
| | - Yan Yang
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China
| | - Shu Yang
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China.
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
| | - Lei Li
- Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, No. 174, Shapingba Street, Chongqing, 400045, China
| | - Liyan Song
- School of resources and environmental engineering, Anhui University, No 111 Jiulong Road, Economic and Technology Development Zone, Hefei, 230601, People's Republic of China.
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19
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Zhou Y, Li S, Hintelmann H, Tang W, Zhong H. New insights into HgSe antagonism: Minor impact on inorganic Hg mobility while potential impacts on microorganisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 913:169705. [PMID: 38160847 DOI: 10.1016/j.scitotenv.2023.169705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/13/2023] [Accepted: 12/25/2023] [Indexed: 01/03/2024]
Abstract
Selenium (Se) is a crucial antagonistic factor of mercury (Hg) methylation in soil, with the transformation of inorganic Hg (IHg) to inert mercury selenide (HgSe) being the key mechanism. However, little evidence has been provided of the reduced Hg mobility at environmentally relevant doses of Hg and Se, and the potential impacts of Se on the activities of microbial methylators have been largely ignored. This knowledge gap hinders effective mitigation for methylmercury (MeHg) risks, considering that Hg supply and microbial methylators serve as materials and workers for MeHg production in soils. By monitoring the mobility of IHg and microbial activities after Se spike, we reported that 1) active methylation might be the premise of HgSe antagonism, as higher decreases in MeHg net production were found in soils with higher constants of Hg methylation rate; 2) IHg mobility did not significantly change upon Se addition in soils with high DOC concentrations, challenging the long-held view of Hg immobilization by Se; and 3) the activities of iron-reducing bacteria (FeRB), an important group of microbial methylators, might be potentially regulated by Se addition at a dose of 4 mg/kg. These findings provide empirical evidence that IHg mobility may not be the limiting factor under Se amendment and suggest the potential impacts of Se on microbial activities.
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Affiliation(s)
- Yang Zhou
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Shouying Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China
| | - Holger Hintelmann
- Department of Chemistry, Trent University, Peterborough, ON, Canada; Water Quality Centre, Trent University, Peterborough, ON, Canada
| | - Wenli Tang
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu Province, China.
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20
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Cao H, Mao K, Zhang H, Wu Q, Ju H, Feng X. Thermal stability and micrdose-based coupling CRISPR/Cas12a biosensor for amplification-free detection of hgcA gene in paddy soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 909:168536. [PMID: 37977400 DOI: 10.1016/j.scitotenv.2023.168536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/21/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023]
Abstract
The lack of point-of-use (POU) methods hinders the utilization of the hgcA gene to rapidly evaluate methylmercury risks. CRISPR/Cas12a is a promising technology, but shortcomings such as low sensitivity, a strict reaction temperature and high background signal limit its further utilization. Here, a thermally stable microsystem-based CRISPR/Cas12a biosensor was constructed to achieve POU analysis for hgcA. First, three target gRNAs were designed to recognize hgcA. Then, a microsystem was developed to eliminate the background signal. Next, the effect of temperature on the activity of the Cas12a-gRNA complex was explored and its thermal stability was discovered. After that, coupling gRNA assay was introduced to improve sensitivity, exhibiting a limit of detection as low as 0.49 pM with a linear range of 0.98-125 pM, and a recovery rate between 90 and 110 % for hgcA. The biosensor was finally utilized to assess hgcA abundance in paddy soil, and high abundance of hgcA was found in these paddy soil samples. This study not only systematically explored the influence of temperature and microsystem on CRISPR/Cas12a, providing vital references for other novel CRISPR-based detection methods, but also applied the CRISPR-based analytical method to the field of environmental geochemistry for the first time, demonstrating enormous potential for POU detection in this field.
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Affiliation(s)
- Haorui Cao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kang Mao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Hua Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Qingqing Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huangxian Ju
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
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21
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Li Z, Wang T, Yang X, Wen X, Chen W, He Y, Yu Z, Zhang C. Microbial community function and methylmercury production in oxygen-limited paddy soil. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 266:115585. [PMID: 37856980 DOI: 10.1016/j.ecoenv.2023.115585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 10/03/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023]
Abstract
Methylmercury is a neurotoxic compound that can enter rice fields through rainfall or irrigation with contaminated wastewater, and then contaminate the human food chain through the consumption of rice. Flooded paddy soil has a porous structure that facilitates air exchange with the atmosphere, but the presence of trace amounts of oxygen in flooded rice field soil and its impact on microbial-mediated formation of methylmercury is still unclear. We compared the microbial communities and their functions in oxygen-depleted and oxygen-limited paddy soil. We discovered that oxygen-limited paddy soil had higher methylmercury concentration, which was strongly correlated with soil properties and methylation potential. Compared with oxygen-depleted soil, oxygen-limited soil altered the microbial composition based on 16 S rRNA sequences, but not based on hgcA sequences. Moreover, oxygen-limited soil enhanced microbial activity significantly, increasing the abundance of more than half of the KEGG pathways, especially the metabolic pathways that might be involved in methylation. Our study unveils how microbial communities influence methylmercury formation in oxygen-limited paddy soil. ENVIRONMENTAL IMPLICATIONS: This study examined how low oxygen input affects microbial-induced MeHg formation in anaerobic paddy soil. We found that oxygen-limited soil produced more MeHg than oxygen-depleted soil. Oxygen input altered the microbial community structure of 16 S rRNA sequencing in anaerobic paddy soil, but had little impact on the hgcA sequencing community structure. Microbial activity and metabolic functions related to MeHg formation were also higher in oxygen-limited paddy soil. We suggest that oxygen may not be a limiting factor for Hg methylators, and that insufficient oxygen input in flooded paddy soil increases the risk of human exposure to MeHg from rice consumption.
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Affiliation(s)
- Zihao Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Tantan Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Xin Wen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Wenhao Chen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Yubo He
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China
| | - Zhigang Yu
- Australian Center for Water and Environmental Biotechnology, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
| | - Chang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, China.
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22
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Wu Q, Wang B, Hu H, Bravo AG, Bishop K, Bertilsson S, Meng B, Zhang H, Feng X. Sulfate-reduction and methanogenesis are coupled to Hg(II) and MeHg reduction in rice paddies. JOURNAL OF HAZARDOUS MATERIALS 2023; 460:132486. [PMID: 37690197 DOI: 10.1016/j.jhazmat.2023.132486] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/17/2023] [Accepted: 09/03/2023] [Indexed: 09/12/2023]
Abstract
Methylmercury (MeHg) produced in rice paddies is the main source of MeHg accumulation in rice, resulting in high risk of MeHg exposure to humans and wildlife. Net MeHg production is affected by Hg(II) reduction and MeHg demethylation, but it remains unclear to what extent these processes influence net MeHg production, as well as the role of the microbial guilds involved. We used isotopically labeled Hg species and specific microbial inhibitors in microcosm experiments to simultaneously investigate the rates of Hg(II) and MeHg transformations, as well as the key microbial guilds controlling these processes. Results showed that Hg(II) and MeHg reduction rate constants significantly decreased with addition of molybdate or BES, which inhibit sulfate-reduction and methanogenesis, respectively. This suggests that both sulfate-reduction and methanogenesis are important processes controlling Hg(II) and MeHg reduction in rice paddies. Meanwhile, up to 99% of MeHg demethylation was oxidative demethylation (OD) under the incubation conditions, suggesting that OD was the main MeHg degradative pathway in rice paddies. In addition, [202Hg(0)/Me202Hg] from the added 202Hg(NO3)2 was up to 13.9%, suggesting that Hg(II) reduction may constrain Hg(II) methylation in rice paddies at the abandoned Hg mining site. This study improves our understanding of Hg cycling pathways in rice paddies, and more specifically how reduction processes affect net MeHg production and related microbial metabolisms.
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Affiliation(s)
- Qingqing Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Baolin Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Haiyan Hu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Andrea G Bravo
- Department of Marine Biology and Oceanography, Institut de Ciencies del Mar (ICM-CSIC), Barcelona E08003, Catalunya, Spain
| | - Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Hua Zhang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
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23
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Liu C, Ning Y, Liu J. Geochemical mercury pools regulate diverse communities of hgcA microbes and MeHg levels in paddy soils. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 334:122172. [PMID: 37437760 DOI: 10.1016/j.envpol.2023.122172] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/26/2023] [Accepted: 07/09/2023] [Indexed: 07/14/2023]
Abstract
Rice paddies are unique artificial wetlands generating methylmercury (MeHg), a highly potent neurotoxin. However, the impact of diverse mercury (Hg) pools on the Hg-methylating communities during rice growth is unclear. This study investigates soil treated with five mercury forms (HgCl2, α-HgS, β-HgS, nano-HgS, and Hg-DOM) at two levels (5 mg/kg and 50 mg/kg). The results showed a varying abundance of sulphate-reducing bacteria, Geobacteraceae, methanogens, and hgcA microbes in the soils across rice grown under different mercury treatments and concentrations. Soils treated with HgCl2, nano-HgS and β-HgS had higher than average levels of hgcA-methanogen abundance, and the abundance significantly and positively correlated with MeHg concentration in all samples (p < 0.05). The shifting trends in Hg-methylating microbial structure following treatment with α-HgS, β-HgS, nano-HgS and Hg-DOM at both 5 and 50 mg/kg Hg levels were diverse compared with the control group. HgCl2 treatment showed contrasting trends in community distribution of Hg methylators at 5 and 50 mg/kg Hg levels during rice growth. Dissolved organic carbon, redox potential and sulphate levels significantly correlated with variation in the Hg-methylating microbial community structure and MeHg production in soils.
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Affiliation(s)
- Chutong Liu
- Hubei Key Laboratory of Critical Zone Evolution, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China; Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan, 430074, China; Key Laboratory of Functional Geomaterials in China Nonmetallic Minerals Industry, China University of Geosciences, Wuhan, 430074, China
| | - Yongqiang Ning
- Hubei Key Laboratory of Critical Zone Evolution, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China; Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan, 430074, China; Key Laboratory of Functional Geomaterials in China Nonmetallic Minerals Industry, China University of Geosciences, Wuhan, 430074, China
| | - Jinling Liu
- Hubei Key Laboratory of Critical Zone Evolution, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China; Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan, 430074, China; Key Laboratory of Functional Geomaterials in China Nonmetallic Minerals Industry, China University of Geosciences, Wuhan, 430074, China.
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24
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Peterson BD, Poulin BA, Krabbenhoft DP, Tate MT, Baldwin AK, Naymik J, Gastelecutto N, McMahon KD. Metabolically diverse microorganisms mediate methylmercury formation under nitrate-reducing conditions in a dynamic hydroelectric reservoir. THE ISME JOURNAL 2023; 17:1705-1718. [PMID: 37495676 PMCID: PMC10504345 DOI: 10.1038/s41396-023-01482-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/13/2023] [Accepted: 07/14/2023] [Indexed: 07/28/2023]
Abstract
Brownlee Reservoir is a mercury (Hg)-impaired hydroelectric reservoir that exhibits dynamic hydrological and geochemical conditions and is located within the Hells Canyon Complex in Idaho, USA. Methylmercury (MeHg) contamination in fish is a concern in the reservoir. While MeHg production has historically been attributed to sulfate-reducing bacteria and methanogenic archaea, microorganisms carrying the hgcA gene are taxonomically and metabolically diverse and the major biogeochemical cycles driving mercury (Hg) methylation are not well understood. In this study, Hg speciation and redox-active compounds were measured throughout Brownlee Reservoir across the stratified period in four consecutive years (2016-2019) to identify the location where and redox conditions under which MeHg is produced. Metagenomic sequencing was performed on a subset of samples to characterize the microbial community with hgcA and identify possible links between biogeochemical cycles and MeHg production. Biogeochemical profiles suggested in situ water column Hg methylation was the major source of MeHg. These profiles, combined with genome-resolved metagenomics focused on hgcA-carrying microbes, indicated that MeHg production occurs in this system under nitrate- or manganese-reducing conditions, which were previously thought to preclude Hg-methylation. Using this multidisciplinary approach, we identified the cascading effects of interannual variability in hydrology on the redox status, microbial metabolic strategies, abundance and metabolic diversity of Hg methylators, and ultimately MeHg concentrations throughout the reservoir. This work expands the known conditions conducive to producing MeHg and suggests that the Hg-methylation mitigation efforts by nitrate or manganese amendment may be unsuccessful in some locations.
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Affiliation(s)
- Benjamin D Peterson
- Department of Civil and Environmental Engineering, University of Wisconsin - Madison, Madison, WI, 53706, USA.
- Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, 53706, USA.
- Department of Environmental Toxicology, University of California - Davis, Davis, CA, 95616, USA.
| | - Brett A Poulin
- Department of Environmental Toxicology, University of California - Davis, Davis, CA, 95616, USA
| | - David P Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, Madison, WI, 53726, USA
| | - Michael T Tate
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, Madison, WI, 53726, USA
| | - Austin K Baldwin
- U.S. Geological Survey, Idaho Water Science Center, Boise, ID, 83702, USA
| | | | | | - Katherine D McMahon
- Department of Civil and Environmental Engineering, University of Wisconsin - Madison, Madison, WI, 53706, USA
- Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, 53706, USA
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25
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Guo P, Rennenberg H, Du H, Wang T, Gao L, Flemetakis E, Hänsch R, Ma M, Wang D. Bacterial assemblages imply methylmercury production at the rice-soil system. ENVIRONMENT INTERNATIONAL 2023; 178:108066. [PMID: 37399771 DOI: 10.1016/j.envint.2023.108066] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/03/2023] [Accepted: 06/24/2023] [Indexed: 07/05/2023]
Abstract
The plant microbiota can affect plant health and fitness by promoting methylmercury (MeHg) production in paddy soil. Although most well-known mercury (Hg) methylators are observed in the soil, it remains unclear how rice rhizosphere assemblages alter MeHg production. Here, we used network analyses of microbial diversity to identify bulk soil (BS), rhizosphere (RS) and root bacterial networks during rice development at Hg gradients. Hg gradients greatly impacted the niche-sharing of taxa significantly relating to MeHg/THg, while plant development had little effect. In RS networks, Hg gradients increased the proportion of MeHg-related nodes in total nodes from 37.88% to 45.76%, but plant development enhanced from 48.59% to 50.41%. The module hub and connector in RS networks included taxa positively (Nitrososphaeracea, Vicinamibacteraceae and Oxalobacteraceae) and negatively (Gracilibacteraceae) correlating with MeHg/THg at the blooming stage. In BS networks, Deinococcaceae and Paludibacteraceae were positively related to MeHg/THg, and constituted the connector at the reviving stage and the module hub at the blooming stage. Soil with an Hg concentration of 30 mg kg-1 increased the complexity and connectivity of root microbial networks, although microbial community structure in roots was less affected by Hg gradients and plant development. As most frequent connector in root microbial networks, Desulfovibrionaceae did not significantly correlate with MeHg/THg, but was likely to play an important role in the response to Hg stress.
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Affiliation(s)
- Pan Guo
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, China
| | - Heinz Rennenberg
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, China
| | - Hongxia Du
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, China
| | - Tao Wang
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, China
| | - Lan Gao
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, China
| | - Emmanouil Flemetakis
- Laboratory of Molecular Biology, Department of Biotechnology, Agricultural University of Athens, 11855 Athens, Greece
| | - Robert Hänsch
- Institute for Plant Biology, Technische Universität Braunschweig, Humboldtstraße 1, D-38106 Braunschweig, Germany
| | - Ming Ma
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing, China; Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing, China.
| | - Dingyong Wang
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Chongqing, China
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26
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Zhang R, Aris-Brosou S, Storck V, Liu J, Abdelhafiz MA, Feng X, Meng B, Poulain AJ. Mining-impacted rice paddies select for Archaeal methylators and reveal a putative (Archaeal) regulator of mercury methylation. ISME COMMUNICATIONS 2023; 3:74. [PMID: 37454192 PMCID: PMC10349881 DOI: 10.1038/s43705-023-00277-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/19/2023] [Accepted: 06/22/2023] [Indexed: 07/18/2023]
Abstract
Methylmercury (MeHg) is a microbially produced neurotoxin derived from inorganic mercury (Hg), which accumulation in rice represents a major health concern to humans. However, the microbial control of MeHg dynamics in the environment remains elusive. Here, leveraging three rice paddy fields with distinct concentrations of Hg (Total Hg (THg): 0.21-513 mg kg-1 dry wt. soil; MeHg: 1.21-6.82 ng g-1 dry wt. soil), we resorted to metagenomics to determine the microbial determinants involved in MeHg production under contrasted contamination settings. We show that Hg methylating Archaea, along with methane-cycling genes, were enriched in severely contaminated paddy soils. Metagenome-resolved Genomes of novel putative Hg methylators belonging to Nitrospinota (UBA7883), with poorly resolved taxonomy despite high completeness, showed evidence of facultative anaerobic metabolism and adaptations to fluctuating redox potential. Furthermore, we found evidence of environmental filtering effects that influenced the phylogenies of not only hgcA genes under different THg concentrations, but also of two housekeeping genes, rpoB and glnA, highlighting the need for further experimental validation of whether THg drives the evolution of hgcAB. Finally, assessment of the genomic environment surrounding hgcAB suggests that this gene pair may be regulated by an archaeal toxin-antitoxin (TA) system, instead of the more frequently found arsR-like genes in bacterial methylators. This suggests the presence of distinct hgcAB regulation systems in bacteria and archaea. Our results support the emerging role of Archaea in MeHg cycling under mining-impacted environments and shed light on the differential control of the expression of genes involved in MeHg formation between Archaea and Bacteria.
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Affiliation(s)
- Rui Zhang
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Stéphane Aris-Brosou
- Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
- Department of Mathematics and Statistics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Veronika Storck
- Department of Civil Engineering, Polytechnique Montréal, Montréal, QC, H3C 3A7, Canada
| | - Jiang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Mahmoud A Abdelhafiz
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
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Yang N, Hu J, Yin D, He T, Tian X, Ran S, Zhou X. Mercury and methylmercury in Hg-contaminated paddy soil and their uptake in rice as regulated by DOM from different agricultural sources. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27712-9. [PMID: 37249779 DOI: 10.1007/s11356-023-27712-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/13/2023] [Indexed: 05/31/2023]
Abstract
In this study, from the perspectives of structural and compositional variations of soil-dissolved organic matter (DOM), we explored the effects of agricultural DOM inputs on methylmercury (MeHg) accumulation in the soil and mercury (Hg) bioaccumulation in rice grains. Pot experiments with the addition of DOMs from maize straw (MaS), rape straw (RaS), rice straw (RiS), composted rice straw (CRiS), cow dung (CD), and composted cow dung (CCD) were then conducted. Results showed that, relative to the control, the DOM amendment from each agricultural source elevated MeHg concentrations in the soil, with an increase of 18-227%, but only parts of DOMs elevated total dissolved Hg (DHg) and MeHg (DMeHg) concentrations in pore water. Among all DOM species, RiS, CRiS, and CCD significantly increased total Hg (THg) and MeHg contents in rice grains by 34-64% and 32-118%, respectively. Compared with RiS, THg and MeHg contents in rice grains in the CRiS treatment decreased slightly, which was consistent with the distributions of DHg and DMeHg concentrations in pore water and the aromaticity variation of soil DOM. In contrast, the CCD input significantly enhanced the enrichment of THg and MeHg in rice grains relative to CD because it significantly reduced the humification of soil DOM at all rice-growing stages while increasing the low-molecular-weight fractions in soil DOM. The THg and MeHg contents in the rice grains were significantly lower treated by RaS than those by MaS and RiS, which may be related to the higher sulfur-containing compounds such as sulfate and cysteine in rape straw or its DOM solution. Overall, DOM amendment from different agricultural sources resulted in significantly discriminative effects on the MeHg accumulation in soil and Hg enrichment in rice in the Hg-contaminated paddy field by shaping soil DOM properties.
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Affiliation(s)
- Ningla Yang
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Jie Hu
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China.
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China.
| | - Xiang Tian
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Shu Ran
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
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Hao YY, Liu HW, Zhao J, Feng J, Hao X, Huang Q, Gu B, Liu YR. Plastispheres as hotspots of microbially-driven methylmercury production in paddy soils. JOURNAL OF HAZARDOUS MATERIALS 2023; 457:131699. [PMID: 37270960 DOI: 10.1016/j.jhazmat.2023.131699] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/09/2023] [Accepted: 05/23/2023] [Indexed: 06/06/2023]
Abstract
Microplastics (MPs) as emerging contaminants have accumulated extensively in agricultural ecosystems and are known to exert important effects on biogeochemical processes. However, how MPs in paddy soils influence the conversion of mercury (Hg) to neurotoxic methylmercury (MeHg) remains poorly understood. Here, we evaluated the effects of MPs on Hg methylation and associated microbial communities in microcosms using two typical paddy soils in China (i.e., yellow and red soils). Results showed that the addition of MPs significantly increased MeHg production in both soils, which could be related to higher Hg methylation potential in the plastisphere than in the bulk soil. We found significant divergences in the community composition of Hg methylators between the plastisphere and the bulk soil. In addition, the plastisphere had higher proportions of Geobacterales in the yellow soil and Methanomicrobia in the red soil compared with the bulk soil, respectively; and plastisphere also had more densely connected microbial groups between non-Hg methylators and Hg methylators. These microbiota in the plastisphere are different from those in the bulk soil, which could partially account for their distinct MeHg production ability. Our findings suggest plastisphere as a unique biotope for MeHg production and provide new insights into the environment risks of MP accumulation in agricultural soils.
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Affiliation(s)
- Yun-Yun Hao
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Hui-Wen Liu
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiating Zhao
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
| | - Jiao Feng
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiuli Hao
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Qiaoyun Huang
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Yu-Rong Liu
- National Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China.
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29
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Wang Y, Chen L, Chen Y, Xue Y, Liu G, Zheng X, Zhou L, Zhong H. Effects of varying amounts of different biochars on mercury methylation in paddy soils and methylmercury accumulation in rice (Oryza sativa L.). THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 874:162459. [PMID: 36871735 DOI: 10.1016/j.scitotenv.2023.162459] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 02/17/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
There is growing evidence for the potential of biochars (BCs) in remediating mercury-contaminated paddy soils, but the high doses commonly used in laboratory studies discourage BC application in practice. To address these difficulties, we compared the effects of varying amounts of BCs from different sources on the formation of methylmercury (MeHg) in soil and its accumulation in rice through microcosm and pot experiments. The addition of a wide range of added doses (0.3, 0.6, 1, 2, 4 and 5 %, w/w) of BCs derived from different biomass feedstocks (i.e., corn stalk, wheat straw, bamboo, oak and poplar) significantly decreased the fraction of ammonium thiosulfate ((NH4)2S2O3)-extractable MeHg in the soil, although the MeHg contents varied with BC types and doses during soil incubation. However, the extractable MeHg in the soil did not continuously decrease with increasing BC doses, especially at doses of >1 %, resulting in limited further reductions. Moreover, a relatively low application rate (0.3-0.6 %, w/w) of BCs (i.e., corn stalk, wheat straw and bamboo-derived BC), especially of bamboo-derived BCs, significantly decreased the MeHg levels (42-76 %) in rice grains (brown rice). Meanwhile, the extractable soil MeHg decreased (57-85 %), although the MeHg in the soil varied under BC amendment during rice cultivation. These results provide further evidence that applying BC produced from different raw carbon materials (e.g., lignocellulosic biomass) could effectively reduce MeHg accumulation in rice grains, possibly due to MeHg bioavailability reduction in the soil. Our results suggest the possibility of mitigating MeHg accumulation in rice with a low dose of BCs, with great potential for use in remediating moderately contaminated paddy soils.
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Affiliation(s)
- Yongjie Wang
- Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, PR China; School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Li Chen
- School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Yuanyuan Chen
- School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Yongjun Xue
- School of Life Sciences, East China Normal University, Shanghai 200241, PR China
| | - Guangxia Liu
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
| | - Xiangmin Zheng
- School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Limin Zhou
- Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, PR China; School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai 200241, PR China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China
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30
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Yang X, Li Z, Wang T, Yang Z, Wen X, Yang K, Huang Y, Chen W, He Y, Shi X, Zhang C, Yu Z. Resupply, diffusion, and bioavailability of Hg in paddy soil-water environment with flood-drain-reflood and straw amendment. ENVIRONMENTAL RESEARCH 2023; 231:116127. [PMID: 37187308 DOI: 10.1016/j.envres.2023.116127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 04/27/2023] [Accepted: 05/11/2023] [Indexed: 05/17/2023]
Abstract
Mercury (Hg) poses a significant risk in paddy fields, particularly when it is converted to methylmercury (MeHg) and accumulates in rice. However, the bioavailability and resupply kinetics of Hg in the paddy soil-water environment are not well understood. In this study, the diffusive gradients in thin films (DGT) and the 'DGT-induced fluxes in sediments' model (DIFS) were first adopted to investigate the Hg resupply kinetics, diffusion fluxes and bioavailability in a paddy environment subjected to flood-drain-reflood treatment and straw amendment. Our results shown that although the straw amendment limited the bioavailability of Hg (38.2%-47.9% lower than control) in porewater by decreasing its resupply capacity, especially with smaller straw particles, the net production of MeHg in paddy fields was significantly increased after straw amendment (73.5%-77.9% higher than control). The results of microbial sequencing indicate that enhanced methylators (e.g., family Geobacter) and non-Hg methylators (e.g., Methanosarcinaceae) played a crucial role in MeHg production following straw amendment. Moreover, Hg-containing paddy soils generally tend to release Hg into the overlying water, while drain-reflood treatment changes the direction of Hg diffusion fluxes in the paddy soil-water interface. The drainage-reflooded treatment decreases the Hg reactive and resupply capacity of the paddy soil, thereby hindering the release of Hg from soil into overlying water during the early stages of reflooding. Overall, this study provides novel insights into the behavior of Hg in paddy soil-water surface microlayers.
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Affiliation(s)
- Xu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Zihao Li
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Tantan Wang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Zhongzhu Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Xin Wen
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Kaihua Yang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Yicai Huang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Wenhao Chen
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Yubo He
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China
| | - Xiaohong Shi
- College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Chang Zhang
- College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, China.
| | - Zhigang Yu
- Australian Centre for Water and Environmental Biotechnology, The University of Queensland, St Lucia, QLD, 4072, Australia.
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Zhu C, Lv S, Zhao Q, Liu X, Wang Z, Zheng X, Zhou L, Wang Y. Seasonal variation in mercury and methylmercury production in vegetated sediment in the Dongtan wetlands of the Yangtze River Estuary, China. MARINE ENVIRONMENTAL RESEARCH 2023; 188:105999. [PMID: 37182325 DOI: 10.1016/j.marenvres.2023.105999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/13/2023] [Accepted: 04/18/2023] [Indexed: 05/16/2023]
Abstract
The seasonal cycling of mercury (Hg) in vegetated sediments in the Dongtan wetlands of the Yangtze River Estuary were determined, and microcosm incubation experiments were conducted to evaluate methylmercury (MeHg) production after Hg input. The results showed that the seasonal variations of total Hg and MeHg were very different. The enhanced activity of methylating bacteria could have been the main contributor to the elevated MeHg in the upper surface layer (0-12 cm), which was supported by the higher copy numbers of the hgcA gene in the surface sediment and the MeHg increase during sediment incubation following litterfall addition. Moreover, the incubation results showed that Hg addition greatly increased net MeHg production and that this increase remained under suboxic conditions, suggesting that the potential health risk of Hg in estuarine wetlands could exist for a long time under changing redox conditions.
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Affiliation(s)
- Changle Zhu
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Shaoyang Lv
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Qing Zhao
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Xia Liu
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China
| | - Zhigang Wang
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China
| | - Xiangmin Zheng
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China
| | - Limin Zhou
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China; Institute of Eco-Chongming, East China Normal University, Shanghai, 200241, PR China
| | - Yongjie Wang
- School of Geographic Sciences, East China Normal University, Shanghai, 200241, PR China; Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai, 200241, PR China.
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32
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Li Y, Dai SS, Zhao J, Hu ZC, Liu Q, Feng J, Huang Q, Gao Y, Liu YR. Amendments of nitrogen and sulfur mitigate carbon-promoting effect on microbial mercury methylation in paddy soils. JOURNAL OF HAZARDOUS MATERIALS 2023; 448:130983. [PMID: 36860084 DOI: 10.1016/j.jhazmat.2023.130983] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/05/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
The imbalance of nutrient elements in paddy soil could affect biogeochemical processes; however, how the key elements input influence microbially-driven conversion of mercury (Hg) to neurotoxic methylmercury (MeHg) remains virtually unknown. Herein, we conducted a series of microcosm experiments to explore the effects of certain species of carbon (C), nitrogen (N) and sulfur (S) on microbial MeHg production in two typical paddy soils (yellow and black soil). Results showed that the addition of C alone into the soils increased MeHg production approximately 2-13 times in the yellow and black soils; while the combined addition of N and C mitigated the C- promoting effect significantly. Added S also had a buffering effect on C-facilitated MeHg production in the yellow soil despite the extent being lower than that of N addition, whereas this effect was not obvious for the black soil. MeHg production was positively correlated with the abundance of Deltaproteobactera-hgcA in both soils, and the changes in MeHg production were related to the shifts of Hg methylating community resulting from C, N, and S imbalance. We further found that the changes in the proportions of dominant Hg methylators such as Geobacter and some unclassified groups could contribute to the variations in MeHg production under different treatments. Moreover, the enhanced microbial syntrophy with adding N and S might contribute to the reduced C-promoting effect on MeHg production. This study has important implications for better understanding of microbes-driven Hg conversion in paddies and wetlands with nutrient elements input.
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Affiliation(s)
- Yunyun Li
- Fujian Provincial Key Laboratory of Ecology-Toxicological Effects & Control for Emerging Contaminants, College of Environmental and Biological Engineering, Putian University, Putian 351100, China
| | - Shu-Shen Dai
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiating Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.
| | - Zhi-Cheng Hu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Qin Liu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiao Feng
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yuxi Gao
- CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
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Zhang J, Li C, Tang W, Wu M, Chen M, He H, Lei P, Zhong H. Mercury in wetlands over 60 years: Research progress and emerging trends. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 869:161862. [PMID: 36716881 DOI: 10.1016/j.scitotenv.2023.161862] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/04/2023] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Wetlands are considered the hotspots for mercury (Hg) biogeochemistry, garnering global attention. Therefore, it is important to review the research progress in this field and predict future frontiers. To achieve that, we conducted a literature analysis by collecting 15,813 publications about Hg in wetlands from the Web of Science Core Collection. The focus of wetland Hg research has changed dramatically over time: 1) In the initial stage (i.e., 1959-1990), research mainly focused on investigating the sources and contents of Hg in wetland environments and fish. 2) For the next 20 years (i.e., 1991-2010), Hg transformation (e.g., Hg reduction and methylation) and environmental factors that affect Hg bioaccumulation have attracted extensive attention. 3) In the recent years of 2011-2022, hot topics in Hg study include microbial Hg methylators, Hg bioavailability, methylmercury (MeHg) demethylation, Hg stable isotope, and Hg cycling in paddy fields. Finally, we put forward future research priorities, i.e., 1) clarifying the primary factors controlling MeHg production, 2) uncovering the MeHg demethylation process, 3) elucidating MeHg bioaccumulation process to better predict its risk, and 4) recognizing the role of wetlands in Hg circulation. This research shows a comprehensive knowledge map for wetland Hg research and suggests avenues for future studies.
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Affiliation(s)
- Jin Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Chengjun Li
- Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
| | - Wenli Tang
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Mengjie Wu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China
| | - Mingying Chen
- School of Environment, Nanjing Normal University, Nanjing 210023, China
| | - Huan He
- School of Environment, Nanjing Normal University, Nanjing 210023, China
| | - Pei Lei
- School of Environment, Nanjing Normal University, Nanjing 210023, China.
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University, Nanjing 210023, China; Environmental and Life Science Program (EnLS), Trent University, Peterborough, Ontario, Canada
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Zhang CJ, Liu YR, Cha G, Liu Y, Zhou XQ, Lu Z, Pan J, Cai M, Li M. Potential for mercury methylation by Asgard archaea in mangrove sediments. THE ISME JOURNAL 2023; 17:478-485. [PMID: 36639538 PMCID: PMC9938162 DOI: 10.1038/s41396-023-01360-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 12/22/2022] [Accepted: 01/06/2023] [Indexed: 01/15/2023]
Abstract
Methylmercury (MeHg) is a potent neurotoxin that bioaccumulates along food chains. The conversion of MeHg from mercury (Hg) is mediated by a variety of anaerobic microorganisms carrying hgcAB genes. Mangrove sediments are potential hotspots of microbial Hg methylation; however, the microorganisms responsible for Hg methylation are poorly understood. Here, we conducted metagenomic and metatranscriptomic analyses to investigate the diversity and distribution of putative microbial Hg-methylators in mangrove ecosystems. The highest hgcA abundance and expression occurred in surface sediments in Shenzhen, where the highest MeHg concentration was also observed. We reconstructed 157 metagenome-assembled genomes (MAGs) carrying hgcA and identified several putative novel Hg-methylators, including one Asgard archaea (Lokiarchaeota). Further analysis of MAGs revealed that Deltaproteobacteria, Euryarchaeota, Bacteroidetes, Chloroflexi, and Lokiarchaeota were the most abundant and active Hg-methylating groups, implying their crucial role in MeHg production. By screening publicly available MAGs, 104 additional Asgard MAGs carrying hgcA genes were identified from a wide range of coast, marine, permafrost, and lake sediments. Protein homology modelling predicts that Lokiarchaeota HgcAB proteins contained the highly conserved amino acid sequences and folding structures required for Hg methylation. Phylogenetic tree revealed that hgcA genes from Asgard clustered with fused hgcAB genes, indicating a transitional stage of Asgard hgcA genes. Our findings thus suggest that Asgard archaea are potential novel Hg-methylating microorganisms and play an important role in hgcA evolution.
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Affiliation(s)
- Cui-Jing Zhang
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070, Wuhan, China
| | - Guihong Cha
- Key Laboratory of Development and Application of Rural Renewable Energy, Biogas Institute of Ministry of Agriculture and Rural Affairs, Chengdu, China
| | - Yang Liu
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
| | - Xin-Quan Zhou
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070, Wuhan, China
| | - Zhongyi Lu
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
| | - Jie Pan
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
| | - Mingwei Cai
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China
- Chemical Biology Institute, Shenzhen Bay Laboratory, Shenzhen, China
| | - Meng Li
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China.
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, 518060, Shenzhen, China.
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Hu H, Gao Y, Yu H, Xiao H, Chen S, Tan W, Tang J, Xi B. Mechanisms and biological effects of organic amendments on mercury speciation in soil-rice systems: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 251:114516. [PMID: 36628877 DOI: 10.1016/j.ecoenv.2023.114516] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 06/17/2023]
Abstract
Mercury (Hg) pollution is a well-recognized global environmental and health issue and exhibits distinctive persistence, neurotoxicity, bioaccumulation, and biomagnification effects. As the largest global Hg reservoir, the Hg cumulatively stored in soils has reached as high as 250-1000 Gg. Even more concerning is that global soil-rice systems distributed in many countries have become central to the global Hg cycle because they are both a major food source for more than 3 billion people worldwide and the central bridge linking atmospheric and soil Hg circulation. In this review, we discuss the form distribution, transformation, and bioavailability of Hg in soil-rice systems by focusing on the Hg methylation and demethylation pathways and distribution, uptake, and accumulation in rice plants and the effects of Hg on the community structure and ecological functions of microorganisms in soil-rice systems. In addition, we clarify the mechanisms through which commonly used humus and biochar organic amendments influence Hg and its environmental effects in soil-rice systems. The review also elaborates on the advantages of sulfur-modified biochars and their critical role in controlling Hg migration and bioavailability in soils. Finally, we provide key information about Hg pollution in soil-rice systems, which is of great significance for developing appropriate strategies and mitigation planning to limit Hg bioconcentration in rice crops and achieving key global sustainable development goals, such as the guarantee of food security and the promotion of sustainable agriculture.
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Affiliation(s)
- Hualing Hu
- Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Yiman Gao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Hanxia Yu
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Haoyan Xiao
- School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China
| | - Shuhe Chen
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Wenbing Tan
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Jun Tang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Beidou Xi
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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Wang B, Hu H, Bishop K, Buck M, Björn E, Skyllberg U, Nilsson MB, Bertilsson S, Bravo AG. Microbial communities mediating net methylmercury formation along a trophic gradient in a peatland chronosequence. JOURNAL OF HAZARDOUS MATERIALS 2023; 442:130057. [PMID: 36179622 DOI: 10.1016/j.jhazmat.2022.130057] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 09/05/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Peatlands are generally important sources of methylmercury (MeHg) to adjacent aquatic ecosystems, increasing the risk of human and wildlife exposure to this highly toxic compound. While microorganisms play important roles in mercury (Hg) geochemical cycles where they directly and indirectly affect MeHg formation in peatlands, potential linkages between net MeHg formation and microbial communities involving these microorganisms remain unclear. To address this gap, microbial community composition and specific marker gene transcripts were investigated along a trophic gradient in a geographically constrained peatland chronosequence. Our results showed a clear spatial pattern in microbial community composition along the gradient that was highly driven by peat soil properties and significantly associated with net MeHg formation as approximated by MeHg concentration and %MeHg of total Hg concentration. Known fermentative, syntrophic, methanogenic and iron-reducing metabolic guilds had the strong positive correlations to net MeHg formation, while methanotrophic and methylotrophic microorganisms were negatively correlated. Our results indicated that sulfate reducers did not have a key role in net MeHg formation. Microbial activity as interpreted from 16S rRNA sequences was significantly correlated with MeHg and %MeHg. Our findings shed new light on the role of microbial community in net MeHg formation of peatlands that undergo ontogenetic change.
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Affiliation(s)
- Baolin Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550081 Guiyang, China; Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Haiyan Hu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550081 Guiyang, China.
| | - Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Moritz Buck
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden
| | - Mats B Nilsson
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-90183 Umeå, Sweden
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - Andrea G Bravo
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar (ICM-CSIC), Pg Marítim de la Barceloneta 37-49, E08003 Barcelona, Catalunya, Spain
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Yang L, Yang G, Wang J, Xiong B, Guo P, Wang T, Du H, Ma M, Wang D. Seasonal changes in total mercury and methylmercury in subtropical decomposing litter correspond to the abundances of nitrogen-fixing and methylmercury-degrading bacteria. JOURNAL OF HAZARDOUS MATERIALS 2023; 442:130064. [PMID: 36182885 DOI: 10.1016/j.jhazmat.2022.130064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
Previous research has found total mercury (THg) and methylmercury (MeHg) levels increase with litterfall decay, thus suggesting litterfall decomposition plays an essential role in the biogeochemical transformation of mercury (Hg). However, it remains unclear how Hg accumulates in the decaying litter, how bacterial taxa networks vary and what roles various microorganisms play during litterfall decomposition, especially nitrogen (N)-fixing, MeHg-degrading and Hg-methylating microbes. Here, we demonstrated as degradation proceeded, a gradually-complex network evolved for litterfall bacteria for the subtropical mixed broadleaf-conifer (MBC) forest, whereas a relatively static network existed for the evergreen broadleaf (EB) forest. N-fixing and MeHg-degrading bacteria dominated throughout litterfall decomposition process, with relative abundances of N-fixing genera and nifH copies maximum and relative abundances of MeHg-degrading bacteria and merAB copies minimum in summer. Hence, N-fixing bacteria likely mediate THg increase in the decomposing litterfall, while MeHg enhancement may be regulated by aerobic MeHg-degrading microbes which can transform MeHg to inorganic divalent Hg (Hg2+) or further to elemental Hg (Hg0). Together, this work elucidates variations of N-fixing and MeHg-degrading microbes in decaying litterfall and their relationships with Hg accumulation, providing novel insights into understanding the biogeochemical cycle of Hg in the forest ecosystem.
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Affiliation(s)
- Liping Yang
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Guang Yang
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Jueying Wang
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Bingcai Xiong
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Pan Guo
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Tao Wang
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Hongxia Du
- Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, China.
| | - Ming Ma
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Bio-resource for Bioenergy, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dingyong Wang
- Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Southwest University, Chongqing 400715, China
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Fan Q, Chen Y, Xu R, Guo Z. Characterization of keystone taxa and microbial metabolic potentials in copper tailing soils. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:1216-1230. [PMID: 35913696 DOI: 10.1007/s11356-022-22294-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Copper mining has caused serious soil contamination and threaten the balance of underground ecosystem. Effects of metal contamination on the soil microbial community assembly and their multifunctionality are still unclear. In this study, the keystone taxa and microbial metabolic potential of soil microorganisms surrounding a typical copper tailing were investigated. Results showed that pH and metal contents of adjacent soil in copper tailing increased, which largely reduced soil microbial communities' diversity. Metal contaminated soils enriched a group of keystone taxa with metal-tolerance such as Bacteroidota (20-54%) and Firmicutes (24-48%), which were distinct from the uncontaminated background soils that dominated by Proteobacteria (19-24%) and Actinobacteria (13-24%). In the contaminated soils, these keystone taxa were identified as Alistipes, Bacteroides, and Faecalibacterium, suggesting their adaptation to the metal-rich environment. Co-occurrence network analysis showed that the microbial community was loosely connected in the metal contaminated soils with a lower number of nodes and links. Co-occurrence networks further revealed that the dynamics of keystone taxa significantly correlated with copper content. Functional gene analysis of soil microorganisms indicated that metal contamination might inhibit important microbial metabolic potentials, such as secondary metabolites biosynthesis, carbon fixation, and nitrogen fixation. Results also found the flexible adaptation strategies of soil microbial communities to metal-rich environments with metal-resistance or bio-transformation, such as efflux (CusB/CusF/CzsB and pcoB/copB) and oxidation (aoxAB). These findings provide insight into the interaction between keystone taxa and soil environment, which is helpful to reveal the microbial metabolic potential and physiological characteristics in tailing contaminated soils.
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Affiliation(s)
- Qiao Fan
- Hunan Research Academy of Environmental Sciences, Changsha, 410014, People's Republic of China
| | - Yeqiang Chen
- Hunan Research Academy of Environmental Sciences, Changsha, 410014, People's Republic of China
| | - Rui Xu
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, People's Republic of China.
| | - Zhaohui Guo
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, People's Republic of China
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Li X, Yang Z, Zhang G, Si S, Wu X, Cai L. Plasmid Genomes Reveal the Distribution, Abundance, and Organization of Mercury-Related Genes and Their Co-Distribution with Antibiotic Resistant Genes in Gammaproteobacteria. Genes (Basel) 2022; 13:2149. [PMID: 36421823 PMCID: PMC9690531 DOI: 10.3390/genes13112149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/13/2022] [Accepted: 11/13/2022] [Indexed: 09/29/2023] Open
Abstract
Mercury (Hg) pollution poses human health and environmental risks worldwide, as it can have toxic effects and causes selective pressure that facilitates the spread of antibiotic resistant genes (ARGs) among microbes. More and more studies have revealed that numerous Hg-related genes (HRGs) can help to resist and transform Hg. In the present study, we systematically analyzed the HRG distribution, abundance, organization, and their co-distribution with ARGs, using 18,731 publicly available plasmid genomes isolated from a Gammaproteobacteria host. Our results revealed that there were many Hg-resistant (mer) operon genes but they were not extensively distributed across plasmids, with only 9.20% of plasmids harboring HRGs. Additionally, no hgcAB genes (which methylate Hg to create methylmercury) were identified in any of the analyzed plasmids. The host source significantly influenced the number of HRGs harbored by plasmids; plasmids isolated from humans and animals harbored a significantly smaller number of HRGs than plasmids isolated from the wastewater and sludge. HRG clusters displayed an extremely high organizational diversity (88 HRG cluster types), though incidences of more than half of the HRG cluster types was <5. This indicates the frequent rearrangement among HRGs in plasmids. The 1368 plasmids harboring both HRGs and ARGs, were dominated by Klebsiella, followed by Escherichia, Salmonella, and Enterobacter. The tightness of the HRG and ARG co-distribution in plasmids was affected by the host sources but not by pathogenicity. HRGs were more likely to co-occur with specific ARG classes (sulfonamide, macrolide-lincosamide-streptogramin, and aminoglycoside resistance genes). Collectively, our results reveal the distribution characteristics of HRGs in plasmids, and they have important implications for further understanding the environmental risks caused by the spread of ARGs through the plasmid-mediated co-transfer of ARGs and HRGs.
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Affiliation(s)
- Xiangyang Li
- School of Life and Health Science, Kaili University, Kaili 556011, China
- Bacterial Genome Data Mining & Bioinformatic Analysis Center, Kaili University, Kaili 556011, China
| | - Zilin Yang
- School of Sciences, Kaili University, Kaili 556018, China
| | - Guohui Zhang
- School of Life and Health Science, Kaili University, Kaili 556011, China
| | - Shengli Si
- School of Life and Health Science, Kaili University, Kaili 556011, China
| | - Xianzhi Wu
- School of Life and Health Science, Kaili University, Kaili 556011, China
| | - Lin Cai
- Shenzhen Institute of Guangdong Ocean University, Shenzhen 518120, China
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Gfeller L, Caplette JN, Frossard A, Mestrot A. Organo-mercury species in a polluted agricultural flood plain: Combining speciation methods and polymerase chain reaction to investigate pathways of contamination. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 311:119854. [PMID: 35998774 DOI: 10.1016/j.envpol.2022.119854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/16/2022] [Accepted: 07/22/2022] [Indexed: 06/15/2023]
Abstract
The analysis of organic mercury (Hg) species in polluted soils is a necessary tool to assess the environmental risk(s) of mercury in contaminated legacy sites. The artificial formation of monomethylmercury (MeHg) during soil extraction and/or analysis is a well-known limitation and is especially relevant in highly polluted areas where MeHg/Hg ratios are notoriously low. Although this has been known for almost 30 years, the thorough characterisation of artificial formation rates is rarely a part of the method development in scientific literature. Here we present the application of two separate procedures (inorganic Hg (iHg) spiking and double-spike isotope dilution analyses (DSIDA)) to determine and correct for artificial Hg methylation in MeHg-selective acid-leaching/organic solvent extraction procedure. Subsequently, we combined corrected MeHg and ethylmercury (EtHg) measurements with PCR amplification of hgcA genes to distinguish between naturally formed MeHg from primary deposited MeHg in soils from a legacy site in a Swiss mountain valley. We found the DSIDA procedure incompatible with the organomercury selective extraction method due to the quantitative removal of iHg. Methylation factors from iHg spiking were in the range of (0.0075 ± 0.0001%) and were consistent across soils and sediment matrices. Further, we suggest that MeHg was deposited and not formed in-situ in two out of three studied locations. Our line of evidence consists of 1) the concomitant detection of EtHg, 2) the elevated MeHg concentrations (up to 4.84 μg kg-1), and 3) the absence of hgcA genes at these locations. The combination of Hg speciation and methylation gene (hgcA) abundance analyses are tools suited to assess Hg pollution pathways at Hg legacy sites.
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Affiliation(s)
- Lorenz Gfeller
- Institute of Geography, University of Bern, Hallerstrasse 12, CH-3012 Bern, Switzerland
| | - Jaime N Caplette
- Institute of Geography, University of Bern, Hallerstrasse 12, CH-3012 Bern, Switzerland
| | - Aline Frossard
- Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Adrien Mestrot
- Institute of Geography, University of Bern, Hallerstrasse 12, CH-3012 Bern, Switzerland.
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Zhou XQ, Qu XM, Yang Z, Zhao J, Hao YY, Feng J, Huang Q, Liu YR. Increased water inputs fuel microbial mercury methylation in upland soils. JOURNAL OF HAZARDOUS MATERIALS 2022; 439:129578. [PMID: 35853337 DOI: 10.1016/j.jhazmat.2022.129578] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/28/2022] [Accepted: 07/09/2022] [Indexed: 06/15/2023]
Abstract
Mercury (Hg) can be converted to neurotoxic methylmercury (MeHg) by certain microbes typically in anaerobic environments, threatening human health due to its bioaccumulation in food webs. However, it is unclear whether and how Hg can be methylated in legacy aerobic uplands with increasing water. Here, we conducted a series of incubation experiments to investigate the effects of increased water content on MeHg production in two typical upland soils (i.e., long-term and short-term use). Results showed that marked MeHg production occurred in water-saturated upland soils, which was strongly correlated with the proportions of significantly stimulated Hg methylating taxon (i.e., Geobacter). Elevated temperature further enhanced MeHg production by blooming proportions of typical Hg methylators (i.e., Clostridium, Acetonema, and Geobacter). Water saturation could also enhance microbial Hg methylation by facilitating microbial syntrophy between non-Hg methylators and Hg methylators. Taken together, the present work suggests that uplands could turn into a potential MeHg reservoir in response to water inputs resulting from rainfall or anthropogenic irrigation.
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Affiliation(s)
- Xin-Quan Zhou
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiao-Min Qu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Ziming Yang
- Department of Chemistry, Oakland University, Rochester, MI 48309, United States
| | - Jiating Zhao
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, PR China.
| | - Yun-Yun Hao
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Jiao Feng
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology and College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China.
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Ran S, He T, Zhou X, Yin D. Effects of fulvic acid and humic acid from different sources on Hg methylation in soil and accumulation in rice. J Environ Sci (China) 2022; 119:93-105. [PMID: 35934469 DOI: 10.1016/j.jes.2022.02.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 06/15/2023]
Abstract
Humus is often used as an organic modifier to reduce the bioaccumulation of heavy metals in plants, but the effects of different humus components from different sources on the fate of mercury (Hg) in paddy fields are still unclear. Here, fulvic acid (FA) and humic acid (HA) extracted from composted straw (CS), composted cow dung (CCD), peat soil (PM) and lignite coal (LC) were used to understand their effects on the methylation and bioaccumulation of Hg in paddy soil by pot experiments. Amendments of both FA and HA largely increased the abundance of Hg-methylating microbes and low-molecular-weight organic matters (e.g, cysteine) in paddy soil. They were also found to change the aromaticity, molecular size and Chromophoric DOM concentration of DOM, and resulted in heterogeneous effects on migration and transformation of Hg. All the FA-amended treatments increased the mobility and methylation of Hg in soil and its absorption in roots. Nevertheless, FA from different sources have heterogeneous effects on transport of Hg between rice tissues. FA-CCD and FA-PM promoted the translocation of MeHg from roots to rice grains by 32.95% and 41.12%, while FA-CS and FA-LC significantly inhibited the translocation of inorganic Hg (IHg) by 52.65% and 66.06% and of MeHg by 46.65% and 36.23%, respectively. In contrast, all HA-amended treatments reduced the mobility of soil Hg, but promoted Hg methylation in soil. Among which, HA-CCD and HA-PM promoted the translocation of MeHg in rice tissues by 88.95% and 64.10%, while its accumulation in rice grains by 28.43% and 28.69%, respectively. In general, the application of some FA and HA as organic modifiers to reduce Hg bioaccumulation in rice is not feasible.
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Affiliation(s)
- Shu Ran
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China.
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China; College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, Guiyang 550025, China.
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Wang J, Xiang Y, Tian X, Zhang C, Gong G, Xue J, Jiang T, Wang D, Wang Y. Role of the rhizosphere of a flooding-tolerant herb in promoting mercury methylation in water-level fluctuation zones. J Environ Sci (China) 2022; 119:139-151. [PMID: 35934459 DOI: 10.1016/j.jes.2022.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/26/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
The water-level fluctuation zone (WLFZ) has been considered as a hotspot for mercury (Hg) methylation. Flooding-tolerant herbs are gradually acclimated to this water-land ecotone, tending to form substantial root systems for improving erosion resistance. Accompanying rhizosphere microzone plays crucial but unclear roles in methylmercury (MeHg) formation in the WLFZ. Thus, we conducted this study in the WLFZ of the Three Gorges Reservoir, to explore effects of the rhizosphere of a dominant flooding-tolerant herb (bermudagrass) on MeHg production. The elevated Hg and MeHg in rhizosphere soils suggest that the rhizosphere environment provides favorable conditions for Hg accumulation and methylation. The increased bioavailable Hg and microbial activity in the rhizosphere probably serve as important factors driving MeHg formation in the presence of bermudagrass. Simultaneously, the rhizosphere environments changed the richness, diversity, and distribution of hgcA-containing microorganisms. Here, a typical iron-reducing bacterium (Geobacteraceae) has been screened, however, the majority of hgcA genes detected in rhizosphere, near-, and non-rhizosphere soils of the WLFZ were unclassified. Collectively, these results provide new insights into the elevated MeHg production as related to microbial processes in the rhizosphere of perennial herbs in the WLFZ, with general implications for Hg cycling in other ecosystems with water-level fluctuations.
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Affiliation(s)
- Juan Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yuping Xiang
- Laboratory of Environmental Nanotechnology & Health Effect, Chinese Academy of Sciences, Research Center for Eco-Environmental Sciences, Beijing 100085, China
| | - Xiaosong Tian
- College of Resources and Safety, Chongqing Vocational Institute of Engineering, Chongqing 402260, China
| | - Cheng Zhang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Guiqing Gong
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Jinping Xue
- Institut des Sciences Analytiques et des Physico-Chimie pour l'Environnement et les Matériaux (IPREM), UMR 5254, CNRS, Université de Pau et des Pays de l'Adour, Pau 64000, France
| | - Tao Jiang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China.
| | - Yongmin Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing 400715, China.
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Tang W, Tang C, Lei P. Sulfur-driven methylmercury production in paddies continues following soil oxidation. J Environ Sci (China) 2022; 119:166-174. [PMID: 35934461 DOI: 10.1016/j.jes.2022.07.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 07/09/2022] [Accepted: 07/10/2022] [Indexed: 06/15/2023]
Abstract
Methylmercury (MeHg) production in paddy soils and its accumulation in rice raise global concerns since rice consumption has been identified as an important pathway of human exposure to MeHg. Sulfur (S) amendment via fertilization has been reported to facilitate Hg methylation in paddy soils under anaerobic conditions, while the dynamic of S-amendment induced MeHg production in soils with increasing redox potential remains unclear. This critical gap hinders a comprehensive understanding of Hg biogeochemistry in rice paddy system which is characterized by the fluctuation of redox potential. Here, we conducted soil incubation experiments to explore MeHg production in slow-oxidizing paddy soils amended with different species of S and doses of sulfate. Results show that the elevated redox potential (1) increased MeHg concentrations by 10.9%-35.2%, which were mainly attributed to the re-oxidation of other S species to sulfate and thus the elevated abundance of sulfate-reducing bacteria, and (2) increased MeHg phytoavailability by up to 75% due to the reductions in acid volatile sulfide (AVS) that strongly binds MeHg in soils. Results obtained from this study call for attention to the increased MeHg production and phytoavailability in paddy soils under elevated redox potentials due to water management, which might aggravate the MeHg production induced by S fertilization and thus enhance MeHg accumulation in rice.
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Affiliation(s)
- Wenli Tang
- School of the Environment, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210023, China.
| | - Chao Tang
- School of the Environment, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing 210023, China
| | - Pei Lei
- School of Environment, Nanjing Normal University, Nanjing 210023, China.
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Gao Z, Zheng W, Li Y, Liu Y, Wu M, Li S, Li P, Liu G, Fu X, Wang S, Wang F, Cai Y, Feng X, Gu B, Zhong H, Yin Y. Mercury transformation processes in nature: Critical knowledge gaps and perspectives for moving forward. J Environ Sci (China) 2022; 119:152-165. [PMID: 35934460 DOI: 10.1016/j.jes.2022.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/11/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
The transformation of mercury (Hg) in the environment plays a vital role in the cycling of Hg and its risk to the ecosystem and human health. Of particular importance are Hg oxidation/reduction and methylation/demethylation processes driven or mediated by the dynamics of light, microorganisms, and organic carbon, among others. Advances in understanding those Hg transformation processes determine our capacity of projecting and mitigating Hg risk. Here, we provide a critical analysis of major knowledge gaps in our understanding of Hg transformation in nature, with perspectives on approaches moving forward. Our analysis focuses on Hg transformation processes in the environment, as well as emerging methodology in exploring these processes. Future avenues for improving the understanding of Hg transformation processes to protect ecosystem and human health are also explored.
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Affiliation(s)
- Zhiyuan Gao
- Centre for Earth Observation Science, and Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Wang Zheng
- Institute of Surface-Earth System Science, Tianjin University, Tianjin 300192, China
| | - Yanbin Li
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education and College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China
| | - Yurong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Mengjie Wu
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Shouying Li
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China
| | - Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Guangliang Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Xuewu Fu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Shuxiao Wang
- School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China
| | - Feiyue Wang
- Centre for Earth Observation Science, and Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Yong Cai
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Huan Zhong
- School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China; Environmental and Life Sciences Program (EnLS), Trent University, Peterborough, Ontario K9L 0G2, Canada.
| | - Yongguang Yin
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
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46
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Du S, Li XQ, Hao X, Hu HW, Feng J, Huang Q, Liu YR. Stronger responses of soil protistan communities to legacy mercury pollution than bacterial and fungal communities in agricultural systems. ISME COMMUNICATIONS 2022; 2:69. [PMID: 37938257 PMCID: PMC9723755 DOI: 10.1038/s43705-022-00156-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/18/2022] [Accepted: 07/26/2022] [Indexed: 08/22/2023]
Abstract
Soil pollution is an important stressor affecting biodiversity and ecosystem functioning. However, we lack a holistic understanding of how soil microbial communities respond to heavy metal pollution in agricultural ecosystems. Here, we explored the distribution patterns and inter-kingdom interactions of entire soil microbiome (including bacteria, fungi, and protists) in 47 paired paddy and upland fields along a gradient of legacy mercury (Hg) pollution. We found that the richness and composition of protistan community had stronger responses to Hg pollution than those of bacterial and fungal communities in both paddy and upland soils. Mercury polluted soils harbored less protistan phototrophs but more protistan consumers. We further revealed that long-term Hg pollution greatly increased network complexity of protistan community than that of bacterial and fungal communities, as well as intensified the interactions between protists and the other microorganisms. Moreover, our results consistently indicated that protistan communities had stronger responses to long-term Hg pollution than bacterial and fungal communities in agricultural soils based on structural equation models and random forest analyses. Our study highlights that soil protists can be used as bioindicators of Hg pollution, with important implications for the assessment of contaminated farmlands and the sustainable management of agricultural ecosystems.
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Affiliation(s)
- Shuai Du
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xin-Qi Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiuli Hao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Hang-Wei Hu
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Jiao Feng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China.
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan, 430070, China.
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47
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Cui Y, Wu Q, Liu K, Wang S, Wang X, Jiang T, Meng B, Wu Y, Guo J. Source Apportionment of Speciated Mercury in Chinese Rice Grain Using a High-Resolution Model. ACS ENVIRONMENTAL AU 2022; 2:324-335. [PMID: 37101969 PMCID: PMC10125373 DOI: 10.1021/acsenvironau.1c00061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Rice grain consumption is a primary pathway of human mercury exposure. To trace the source of rice grain mercury in China, we developed a rice paddy mercury transport and transformation model with a grid resolution of 1 km × 1 km by using the unit cell mass conservation method. The simulated total mercury (THg) and methylmercury (MeHg) concentrations in Chinese rice grain ranged from 0.08 to 243.6 and 0.03 to 238.6 μg/kg, respectively, in 2017. Approximately, 81.3% of the national average rice grain THg concentration was due to atmospheric mercury deposition. However, soil heterogeneity, especially the variation in soil mercury, led to the wide rice grain THg distribution across grids. Approximately, 64.8% of the national average rice grain MeHg concentration was due to soil mercury. In situ methylation was the main pathway via which the rice grain MeHg concentration was increased. The coupled impact of high mercury input and methylation potential led to extremely high rice grain MeHg in partial grids among Guizhou province and junctions with surrounding provinces. The spatial variation in soil organic matter significantly impacted the methylation potential among grids, especially in Northeast China. Based on the high-resolution rice grain THg concentration, we identified 0.72% of grids as heavily polluted THg grids (rice grain THg > 20 μg/kg). These grids mainly corresponded to areas in which the human activities of nonferrous metal smelting, cement clinker production, and mercury and other metal mining were conducted. Thus, we recommended measures that are targeted at the control of heavy pollution of rice grain by THg according to the pollution sources. In addition, we observed a wide spatial variation range of MeHg to THg ratios not only in China but also in other regions of the world, which highlights the potential risk of rice intake.
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Affiliation(s)
- Yuying Cui
- State
Key Joint Laboratory of Environment Simulation and Pollution Control,
School of Environment, Tsinghua University, Beijing 100084, China
- State
Environmental Protection Key Laboratory of Sources and Control of
Air Pollution Complex, Beijing 100084, China
| | - Qingru Wu
- State
Key Joint Laboratory of Environment Simulation and Pollution Control,
School of Environment, Tsinghua University, Beijing 100084, China
- State
Environmental Protection Key Laboratory of Sources and Control of
Air Pollution Complex, Beijing 100084, China
| | - Kaiyun Liu
- State
Key Joint Laboratory of Environment Simulation and Pollution Control,
School of Environment, Tsinghua University, Beijing 100084, China
- State
Environmental Protection Key Laboratory of Sources and Control of
Air Pollution Complex, Beijing 100084, China
| | - Shuxiao Wang
- State
Key Joint Laboratory of Environment Simulation and Pollution Control,
School of Environment, Tsinghua University, Beijing 100084, China
- State
Environmental Protection Key Laboratory of Sources and Control of
Air Pollution Complex, Beijing 100084, China
- . Phone: +86
1062771466. Fax: +86 1062773597
| | - Xun Wang
- State
Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Tao Jiang
- Department
of Environmental Science and Engineering, Collage of Resources and
Environment, Southwest University, Chongqing 400716, China
| | - Bo Meng
- State
Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Yurong Wu
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Jia Guo
- State
Key Joint Laboratory of Environment Simulation and Pollution Control,
School of Environment, Tsinghua University, Beijing 100084, China
- State
Environmental Protection Key Laboratory of Sources and Control of
Air Pollution Complex, Beijing 100084, China
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48
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Capo E, Peterson BD, Kim M, Jones DS, Acinas SG, Amyot M, Bertilsson S, Björn E, Buck M, Cosio C, Elias DA, Gilmour C, Goñi Urriza MS, Gu B, Lin H, Liu YR, McMahon K, Moreau JW, Pinhassi J, Podar M, Puente-Sánchez F, Sánchez P, Storck V, Tada Y, Vigneron A, Walsh D, Vandewalle-Capo M, Bravo AG, Gionfriddo C. A consensus protocol for the recovery of mercury methylation genes from metagenomes. Mol Ecol Resour 2022; 23:190-204. [PMID: 35839241 PMCID: PMC10087281 DOI: 10.1111/1755-0998.13687] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/24/2022] [Accepted: 07/08/2022] [Indexed: 11/27/2022]
Abstract
Mercury (Hg) methylation genes (hgcAB) mediate the formation of the toxic methylmercury and have been identified from diverse environments, including freshwater and marine ecosystems, Arctic permafrost, forest and paddy soils, coal-ash amended sediments, chlor-alkali plants discharges and geothermal springs. Here we present the first attempt at a standardized protocol for the detection, identification and quantification of hgc genes from metagenomes. Our Hg-MATE (Hg-cycling Microorganisms in Aquatic and Terrestrial Ecosystems) database, a catalogue of hgc genes, provides the most accurate information to date on the taxonomic identity and functional/metabolic attributes of microorganisms responsible for Hg methylation in the environment. Furthermore, we introduce "marky-coco", a ready-to-use bioinformatic pipeline based on de novo single-metagenome assembly, for easy and accurate characterization of hgc genes from environmental samples. We compared the recovery of hgc genes from environmental metagenomes using the marky-coco pipeline with an approach based on co-assembly of multiple metagenomes. Our data show similar efficiency in both approaches for most environments except those with high diversity (i.e., paddy soils) for which a co-assembly approach was preferred. Finally, we discuss the definition of true hgc genes and methods to normalize hgc gene counts from metagenomes.
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Affiliation(s)
- Eric Capo
- Department of Marine Biology and Oceanography, Institute of Marine Sciences, CSIC, Barcelona, 08003, Spain.,Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Benjamin D Peterson
- Department of Bacteriology, University of Wisconsin at Madison, 53706, Madison, WI, USA
| | - Minjae Kim
- Natural Resource Ecology Laboratory, Colorado State University, 80523, Fort Collins, CO, USA
| | - Daniel S Jones
- Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, 87801, Socorro, NM, USA.,National Cave and Karst Research Institute, 88220, Carlsbad, NM, USA
| | - Silvia G Acinas
- Department of Marine Biology and Oceanography, Institute of Marine Sciences, CSIC, Barcelona, 08003, Spain
| | - Marc Amyot
- Department of Biological Sciences, University of Montréal, Montréal, QC, H3C 5J9, Canada
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, 90736, Umeå, Sweden
| | - Moritz Buck
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Claudia Cosio
- University of Reims Champagne-Ardenne, 51100, Reims, France
| | | | - Cynthia Gilmour
- Smithsonian Environmental Research Center, 21037, Edgewater, MD, USA
| | | | - Baohua Gu
- Oak Ridge National Lab, 37830, Oak Ridge, TN, USA
| | - Heyu Lin
- School of Geography, Earth and Atmospheric Sciences, The University of Melbourne, 3010, Parkville, VIC, Australia
| | - Yu-Rong Liu
- College of Resources and Environment, Huazhong Agricultural University, 430070, Wuhan, China
| | - Katherine McMahon
- Department of Bacteriology, University of Wisconsin at Madison, 53706, Madison, WI, USA
| | - John W Moreau
- School of Geographical and Earth Sciences, University of Glasgow, G12 8RZ, Glasgow, UK
| | - Jarone Pinhassi
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, 39231, Kalmar, Sweden
| | - Mircea Podar
- Oak Ridge National Lab, 37830, Oak Ridge, TN, USA
| | - Fernando Puente-Sánchez
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Pablo Sánchez
- Department of Marine Biology and Oceanography, Institute of Marine Sciences, CSIC, Barcelona, 08003, Spain
| | - Veronika Storck
- Department of Biological Sciences, University of Montréal, Montréal, QC, H3C 5J9, Canada
| | - Yuya Tada
- National Institute for Minamata Disease, Department of Environment and Public Health, Kumamoto, 867-0008, Japan
| | - Adrien Vigneron
- University of Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, 64000, France
| | - David Walsh
- Department of Biology, Concordia University, Montreal, Quebec H4BIR6, Canada
| | - Marine Vandewalle-Capo
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Andrea G Bravo
- Department of Marine Biology and Oceanography, Institute of Marine Sciences, CSIC, Barcelona, 08003, Spain
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49
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Yin X, Wang L, Liang X, Zhang L, Zhao J, Gu B. Contrary effects of phytoplankton Chlorella vulgaris and its exudates on mercury methylation by iron- and sulfate-reducing bacteria. JOURNAL OF HAZARDOUS MATERIALS 2022; 433:128835. [PMID: 35398798 DOI: 10.1016/j.jhazmat.2022.128835] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Mercury (Hg) is a pervasive environmental pollutant and poses serious health concerns as inorganic Hg(II) can be converted to the neurotoxin methylmercury (MeHg), which bioaccumulates and biomagnifies in food webs. Phytoplankton, representing the base of aquatic food webs, can take up Hg(II) and influence MeHg production, but currently little is known about how and to what extent phytoplankton may impact Hg(II) methylation by itself or by methylating bacteria it harbors. This study investigated whether some species of phytoplankton could produce MeHg and how the live or dead phytoplankton cells and excreted algal organic matter (AOM) impact Hg(II) methylation by several known methylators, including iron-reducing bacteria (FeRB), Geobacter anodireducens SD-1 and Geobacter sulfurreducens PCA, and the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans ND132 (or Pseudodesulfovibrio mercurii). Our results indicate that, among the 4 phytoplankton species studied, none were capable of methylating Hg(II). However, the presence of phytoplankton cells (either live or dead) from Chlorella vulgaris (CV) generally inhibited Hg(II) methylation by FeRB but substantially enhanced methylation by SRB D. desulfuricans ND132. Enhanced methylation was attributed in part to CV-excreted AOM, which increased Hg(II) complexation and methylation by ND132 cells. In contrast, inhibition of methylation by FeRB was attributed to these bacteria incapable of competing with phytoplankton for Hg(II) binding and uptake. These observations suggest that phytoplankton could play different roles in affecting Hg(II) methylation by the two groups of anaerobic bacteria, FeRB and SRB, and thus shed additional light on how phytoplankton blooms may modulate MeHg production and bioaccumulation in the aquatic environment.
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Affiliation(s)
- Xixiang Yin
- Shandong Jinan Eco-environmental Monitoring Center, Jinan 250014, China; Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Lihong Wang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States; Qilu University of Technology (Shandong Academy of Sciences), Shandong Analysis and Test Center, Jinan 250014, China
| | - Xujun Liang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Lijie Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Jiating Zhao
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Ten 37831, United States; Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Ten 37996, United States.
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50
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Liu J, Li Y, Duan D, Peng G, Li P, Lei P, Zhong H, Tsui MTK, Pan K. Effects and mechanisms of organic matter regulating the methylmercury dynamics in mangrove sediments. JOURNAL OF HAZARDOUS MATERIALS 2022; 432:128690. [PMID: 35325865 DOI: 10.1016/j.jhazmat.2022.128690] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/09/2022] [Accepted: 03/09/2022] [Indexed: 06/14/2023]
Abstract
Mangrove ecosystems serve as an important carbon sink but also could be a hotspot that produces neurotoxic methylmercury (MeHg). Although many studies have focused on mercury (Hg) contamination in this carbon-rich ecosystem, our understanding of the effects and mechanisms of the organic matter (OM) regulation of MeHg production in mangrove sediments is still limited. Here, we examined the effects of Hg contamination and OM enrichment on MeHg production in anoxic mangrove sediments and identified the major microbial guilds attending this process. The mangrove sediments possessed a high potential for producing MeHg, but this was counterbalanced by its rapid degradation. Sulfate-reducing bacteria (SRB) such as Desulfobacterales, Desulfovibrionales, and Syntrophobacterales were the major methylators. OM diagenesis significantly changed the biogeochemical conditions, accelerating MeHg degradation in the sediments. The enhanced MeHg degradation could be attributed to the abundant sulfide produced during OM decomposition, which could potentially inhibit the Hg methylation by immobilization of inorganic Hg, abiotically degrade MeHg, and favor the non-mer-mediated degradation of MeHg by SRB. Our study provides both geochemical and microbial clues that can partly explain the low MeHg levels widely observed in mangrove sediments.
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Affiliation(s)
- Jingli Liu
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yanping Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Dandan Duan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Guogan Peng
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Ping Li
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Pei Lei
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Huan Zhong
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Martin Tsz-Ki Tsui
- School of Life Sciences, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Ke Pan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China.
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